Stop using a pool of threads for database operations

Now that squee cooperates with suspendable ports, this is unnecessary. Use a
connection pool to still support running queries in parallel using multiple
connections.

1 files changed, 320 insertions, 374 deletions

diff --git a/guix-data-service/web/revision/controller.scm b/guix-data-service/web/revision/controller.scm
index 1cb4528..9cfddd4 100644
--- a/guix-data-service/web/revision/controller.scm
+++ b/guix-data-service/web/revision/controller.scm
@@ -30,6 +30,7 @@
   #:use-module (guix-data-service web sxml)
   #:use-module (guix-data-service web query-parameters)
   #:use-module (guix-data-service web util)
+  #:use-module (guix-data-service web controller)
   #:use-module (guix-data-service model utils)
   #:use-module (guix-data-service jobs load-new-guix-revision)
   #:use-module (guix-data-service model build)
@@ -84,7 +85,7 @@
 
 (define (parse-build-server v)
   (letpar& ((build-servers
-             (with-thread-postgresql-connection select-build-servers)))
+             (with-resource-from-pool (connection-pool) conn select-build-servers)))
     (or (any (match-lambda
                ((id url lookup-all-derivations? lookup-builds?)
                 (if (eq? (string->number v)
@@ -105,20 +106,16 @@
 
   (match method-and-path-components
     (('GET "revision" commit-hash)
-     (if (parallel-via-thread-pool-channel
-          (with-thread-postgresql-connection
-           (lambda (conn)
-             (guix-revision-loaded-successfully? conn commit-hash))))
+     (if (with-resource-from-pool (connection-pool) conn
+           (guix-revision-loaded-successfully? conn commit-hash))
          (render-view-revision mime-types
                                commit-hash
                                #:path-base path)
          (render-unknown-revision mime-types
                                   commit-hash)))
     (('GET "revision" commit-hash "news")
-     (if (parallel-via-thread-pool-channel
-          (with-thread-postgresql-connection
-           (lambda (conn)
-             (guix-revision-loaded-successfully? conn commit-hash))))
+     (if (with-resource-from-pool (connection-pool) conn
+           (guix-revision-loaded-successfully? conn commit-hash))
          (let ((parsed-query-parameters
                 (parse-query-parameters
                  request
@@ -129,10 +126,8 @@
          (render-unprocessed-revision mime-types
                                       commit-hash)))
     (('GET "revision" commit-hash "packages")
-     (if (parallel-via-thread-pool-channel
-          (with-thread-postgresql-connection
-           (lambda (conn)
-             (guix-revision-loaded-successfully? conn commit-hash))))
+     (if (with-resource-from-pool (connection-pool) conn
+           (guix-revision-loaded-successfully? conn commit-hash))
          (let ((parsed-query-parameters
                 (guard-against-mutually-exclusive-query-parameters
                  (parse-query-parameters
@@ -158,30 +153,24 @@
          (render-unprocessed-revision mime-types
                                       commit-hash)))
     (('GET "revision" commit-hash "packages-translation-availability")
-     (if (parallel-via-thread-pool-channel
-          (with-thread-postgresql-connection
-           (lambda (conn)
-             (guix-revision-loaded-successfully? conn commit-hash))))
+     (if (with-resource-from-pool (connection-pool) conn
+           (guix-revision-loaded-successfully? conn commit-hash))
          (render-revision-packages-translation-availability mime-types
                                                             commit-hash
                                                             #:path-base path)
          (render-unprocessed-revision mime-types
                                       commit-hash)))
     (('GET "revision" commit-hash "package" name)
-     (if (parallel-via-thread-pool-channel
-          (with-thread-postgresql-connection
-           (lambda (conn)
-             (guix-revision-loaded-successfully? conn commit-hash))))
+     (if (with-resource-from-pool (connection-pool) conn
+           (guix-revision-loaded-successfully? conn commit-hash))
          (render-revision-package mime-types
                                   commit-hash
                                   name)
          (render-unprocessed-revision mime-types
                                       commit-hash)))
     (('GET "revision" commit-hash "package" name version)
-     (if (parallel-via-thread-pool-channel
-          (with-thread-postgresql-connection
-           (lambda (conn)
-             (guix-revision-loaded-successfully? conn commit-hash))))
+     (if (with-resource-from-pool (connection-pool) conn
+           (guix-revision-loaded-successfully? conn commit-hash))
          (let ((parsed-query-parameters
                 (parse-query-parameters
                  request
@@ -194,10 +183,8 @@
          (render-unprocessed-revision mime-types
                                       commit-hash)))
     (('GET "revision" commit-hash "package-derivations")
-     (if (parallel-via-thread-pool-channel
-          (with-thread-postgresql-connection
-           (lambda (conn)
-             (guix-revision-loaded-successfully? conn commit-hash))))
+     (if (with-resource-from-pool (connection-pool) conn
+           (guix-revision-loaded-successfully? conn commit-hash))
          (let ((parsed-query-parameters
                 (guard-against-mutually-exclusive-query-parameters
                  (parse-query-parameters
@@ -228,10 +215,8 @@
          (render-unprocessed-revision mime-types
                                       commit-hash)))
     (('GET "revision" commit-hash "fixed-output-package-derivations")
-     (if (parallel-via-thread-pool-channel
-          (with-thread-postgresql-connection
-           (lambda (conn)
-             (guix-revision-loaded-successfully? conn commit-hash))))
+     (if (with-resource-from-pool (connection-pool) conn
+           (guix-revision-loaded-successfully? conn commit-hash))
          (let ((parsed-query-parameters
                 (guard-against-mutually-exclusive-query-parameters
                  (parse-query-parameters
@@ -254,10 +239,8 @@
          (render-unprocessed-revision mime-types
                                       commit-hash)))
     (('GET "revision" commit-hash "package-derivation-outputs")
-     (if (parallel-via-thread-pool-channel
-          (with-thread-postgresql-connection
-           (lambda (conn)
-             (guix-revision-loaded-successfully? conn commit-hash))))
+     (if (with-resource-from-pool (connection-pool) conn
+           (guix-revision-loaded-successfully? conn commit-hash))
          (let ((parsed-query-parameters
                 (guard-against-mutually-exclusive-query-parameters
                  (parse-query-parameters
@@ -287,10 +270,8 @@
          (render-unprocessed-revision mime-types
                                       commit-hash)))
     (('GET "revision" commit-hash "system-tests")
-     (if (parallel-via-thread-pool-channel
-          (with-thread-postgresql-connection
-           (lambda (conn)
-             (guix-revision-loaded-successfully? conn commit-hash))))
+     (if (with-resource-from-pool (connection-pool) conn
+           (guix-revision-loaded-successfully? conn commit-hash))
          (let ((parsed-query-parameters
                 (parse-query-parameters
                  request
@@ -302,40 +283,32 @@
          (render-unprocessed-revision mime-types
                                       commit-hash)))
     (('GET "revision" commit-hash "channel-instances")
-     (if (parallel-via-thread-pool-channel
-          (with-thread-postgresql-connection
-           (lambda (conn)
-             (channel-instances-exist-for-guix-revision? conn commit-hash))))
+     (if (with-resource-from-pool (connection-pool) conn
+           (channel-instances-exist-for-guix-revision? conn commit-hash))
          (render-revision-channel-instances mime-types
                                             commit-hash
                                             #:path-base path)
          (render-unprocessed-revision mime-types
                                       commit-hash)))
     (('GET "revision" commit-hash "package-substitute-availability")
-     (if (parallel-via-thread-pool-channel
-          (with-thread-postgresql-connection
-           (lambda (conn)
-             (guix-revision-loaded-successfully? conn commit-hash))))
+     (if (with-resource-from-pool (connection-pool) conn
+           (guix-revision-loaded-successfully? conn commit-hash))
          (render-revision-package-substitute-availability mime-types
                                                           commit-hash
                                                           #:path-base path)
          (render-unprocessed-revision mime-types
                                       commit-hash)))
     (('GET "revision" commit-hash "package-reproducibility")
-     (if (parallel-via-thread-pool-channel
-          (with-thread-postgresql-connection
-           (lambda (conn)
-             (guix-revision-loaded-successfully? conn commit-hash))))
+     (if (with-resource-from-pool (connection-pool) conn
+           (guix-revision-loaded-successfully? conn commit-hash))
          (render-revision-package-reproduciblity mime-types
                                                  commit-hash
                                                  #:path-base path)
          (render-unprocessed-revision mime-types
                                       commit-hash)))
     (('GET "revision" commit-hash "builds")
-     (if (parallel-via-thread-pool-channel
-          (with-thread-postgresql-connection
-           (lambda (conn)
-             (guix-revision-loaded-successfully? conn commit-hash))))
+     (if (with-resource-from-pool (connection-pool) conn
+           (guix-revision-loaded-successfully? conn commit-hash))
          (let ((parsed-query-parameters
                 (guard-against-mutually-exclusive-query-parameters
                  (parse-query-parameters
@@ -357,10 +330,8 @@
          (render-unprocessed-revision mime-types
                                       commit-hash)))
     (('GET "revision" commit-hash "blocking-builds")
-     (if (parallel-via-thread-pool-channel
-          (with-thread-postgresql-connection
-           (lambda (conn)
-             (guix-revision-loaded-successfully? conn commit-hash))))
+     (if (with-resource-from-pool (connection-pool) conn
+           (guix-revision-loaded-successfully? conn commit-hash))
          (let ((parsed-query-parameters
                 (guard-against-mutually-exclusive-query-parameters
                  (parse-query-parameters
@@ -381,10 +352,8 @@
          (render-unprocessed-revision mime-types
                                       commit-hash)))
     (('GET "revision" commit-hash "lint-warnings")
-     (if (parallel-via-thread-pool-channel
-          (with-thread-postgresql-connection
-           (lambda (conn)
-             (guix-revision-loaded-successfully? conn commit-hash))))
+     (if (with-resource-from-pool (connection-pool) conn
+           (guix-revision-loaded-successfully? conn commit-hash))
          (let ((parsed-query-parameters
                 (parse-query-parameters
                  request
@@ -424,18 +393,15 @@
       #:code 404))
     (else
      (letpar& ((job
-                (with-thread-postgresql-connection
-                 (lambda (conn)
-                   (select-job-for-commit conn commit-hash))))
+                (with-resource-from-pool (connection-pool) conn
+                  (select-job-for-commit conn commit-hash)))
                (git-repositories-and-branches
-                (with-thread-postgresql-connection
-                 (lambda (conn)
-                   (git-branches-with-repository-details-for-commit conn
-                                                                    commit-hash))))
+                (with-resource-from-pool (connection-pool) conn
+                  (git-branches-with-repository-details-for-commit conn
+                                                                   commit-hash)))
                (jobs-and-events
-                (with-thread-postgresql-connection
-                 (lambda (conn)
-                   (select-jobs-and-events-for-commit conn commit-hash)))))
+                (with-resource-from-pool (connection-pool) conn
+                  (select-jobs-and-events-for-commit conn commit-hash))))
 
      (render-html
       #:code 404
@@ -455,18 +421,15 @@
       #:code 404))
     (else
      (letpar& ((job
-                (with-thread-postgresql-connection
-                 (lambda (conn)
-                   (select-job-for-commit conn commit-hash))))
+                (with-resource-from-pool (connection-pool) conn
+                  (select-job-for-commit conn commit-hash)))
                (git-repositories-and-branches
-                (with-thread-postgresql-connection
-                 (lambda (conn)
-                   (git-branches-with-repository-details-for-commit conn
-                                                                    commit-hash))))
+                (with-resource-from-pool (connection-pool) conn
+                  (git-branches-with-repository-details-for-commit conn
+                                                                   commit-hash)))
                (jobs-and-events
-                (with-thread-postgresql-connection
-                 (lambda (conn)
-                   (select-jobs-and-events-for-commit conn commit-hash)))))
+                (with-resource-from-pool (connection-pool) conn
+                  (select-jobs-and-events-for-commit conn commit-hash))))
 
      (render-html
       #:code 404
@@ -482,27 +445,22 @@
                                (header-text
                                 `("Revision " (samp ,commit-hash))))
   (letpar& ((packages-count
-             (with-thread-postgresql-connection
-              (lambda (conn)
-                (count-packages-in-revision conn commit-hash))))
+             (with-resource-from-pool (connection-pool) conn
+               (count-packages-in-revision conn commit-hash)))
             (git-repositories-and-branches
-             (with-thread-postgresql-connection
-              (lambda (conn)
-                (git-branches-with-repository-details-for-commit conn
-                                                                 commit-hash))))
+             (with-resource-from-pool (connection-pool) conn
+               (git-branches-with-repository-details-for-commit conn
+                                                                commit-hash)))
             (derivations-counts
-             (with-thread-postgresql-connection
-              (lambda (conn)
-                (count-packages-derivations-in-revision conn commit-hash))))
+             (with-resource-from-pool (connection-pool) conn
+               (count-packages-derivations-in-revision conn commit-hash)))
             (jobs-and-events
-             (with-thread-postgresql-connection
-              (lambda (conn)
-                (select-jobs-and-events-for-commit conn commit-hash))))
+             (with-resource-from-pool (connection-pool) conn
+               (select-jobs-and-events-for-commit conn commit-hash)))
             (lint-warning-counts
-             (with-thread-postgresql-connection
-              (lambda (conn)
-                (lint-warning-count-by-lint-checker-for-revision conn
-                                                                 commit-hash)))))
+             (with-resource-from-pool (connection-pool) conn
+               (lint-warning-count-by-lint-checker-for-revision conn
+                                                                commit-hash))))
     (case (most-appropriate-mime-type
            '(application/json text/html)
            mime-types)
@@ -547,12 +505,11 @@
                                        (header-link
                                         (string-append "/revision/" commit-hash)))
   (letpar& ((system-tests
-             (with-thread-postgresql-connection
-              (lambda (conn)
-                (select-system-tests-for-guix-revision
-                 conn
-                 (assq-ref query-parameters 'system)
-                 commit-hash)))))
+             (with-resource-from-pool (connection-pool) conn
+               (select-system-tests-for-guix-revision
+                conn
+                (assq-ref query-parameters 'system)
+                commit-hash))))
     (case (most-appropriate-mime-type
            '(application/json text/html)
            mime-types)
@@ -576,12 +533,11 @@
                 system-tests))))))
       (else
        (letpar& ((git-repositories
-                  (with-thread-postgresql-connection
-                   (lambda (conn)
-                     (git-repositories-containing-commit conn
-                                                         commit-hash))))
+                  (with-resource-from-pool (connection-pool) conn
+                    (git-repositories-containing-commit conn
+                                                        commit-hash)))
                  (systems
-                  (with-thread-postgresql-connection list-systems)))
+                  (with-resource-from-pool (connection-pool) conn list-systems)))
          (render-html
           #:sxml (view-revision-system-tests
                   commit-hash
@@ -603,9 +559,8 @@
                                              (string-append "/revision/"
                                                             commit-hash)))
   (letpar& ((channel-instances
-             (with-thread-postgresql-connection
-              (lambda (conn)
-                (select-channel-instances-for-guix-revision conn commit-hash)))))
+             (with-resource-from-pool (connection-pool) conn
+               (select-channel-instances-for-guix-revision conn commit-hash))))
     (case (most-appropriate-mime-type
            '(application/json text/html)
            mime-types)
@@ -632,12 +587,12 @@
                                                           commit-hash
                                                           #:key path-base)
   (letpar& ((substitute-availability
-             (with-thread-postgresql-connection
-              (lambda (conn)
-                (select-package-output-availability-for-revision conn
-                                                                 commit-hash))))
+             (with-resource-from-pool (connection-pool) conn
+               (select-package-output-availability-for-revision conn
+                                                                commit-hash)))
             (build-server-urls
-             (with-thread-postgresql-connection
+             (call-with-resource-from-pool
+              (connection-pool)
               select-build-server-urls-by-id)))
     (case (most-appropriate-mime-type
            '(application/json text/html)
@@ -678,9 +633,8 @@
                                                   (string-append "/revision/"
                                                                  commit-hash)))
   (letpar& ((output-consistency
-             (with-thread-postgresql-connection
-              (lambda (conn)
-                (select-output-consistency-for-revision conn commit-hash)))))
+             (with-resource-from-pool (connection-pool) conn
+               (select-output-consistency-for-revision conn commit-hash))))
     (case (most-appropriate-mime-type
            '(application/json text/html)
            mime-types)
@@ -713,11 +667,10 @@
                                      query-parameters
                                      '()))))
       (letpar& ((news-entries
-                 (with-thread-postgresql-connection
-                  (lambda (conn)
-                    (select-channel-news-entries-contained-in-guix-revision
-                     conn
-                     commit-hash)))))
+                 (with-resource-from-pool (connection-pool) conn
+                   (select-channel-news-entries-contained-in-guix-revision
+                    conn
+                    commit-hash))))
         (case (most-appropriate-mime-type
                '(application/json text/html)
                mime-types)
@@ -774,26 +727,24 @@
             (locale (assq-ref query-parameters 'locale)))
         (letpar&
             ((packages
-              (with-thread-postgresql-connection
-               (lambda (conn)
-                 (if search-query
-                     (search-packages-in-revision
-                      conn
-                      commit-hash
-                      search-query
-                      #:limit-results limit-results
-                      #:locale locale)
-                     (select-packages-in-revision
-                      conn
-                      commit-hash
-                      #:limit-results limit-results
-                      #:after-name (assq-ref query-parameters 'after_name)
-                      #:locale (assq-ref query-parameters 'locale))))))
+              (with-resource-from-pool (connection-pool) conn
+                (if search-query
+                    (search-packages-in-revision
+                     conn
+                     commit-hash
+                     search-query
+                     #:limit-results limit-results
+                     #:locale locale)
+                    (select-packages-in-revision
+                     conn
+                     commit-hash
+                     #:limit-results limit-results
+                     #:after-name (assq-ref query-parameters 'after_name)
+                     #:locale (assq-ref query-parameters 'locale)))))
              (git-repositories
-              (with-thread-postgresql-connection
-               (lambda (conn)
-                 (git-repositories-containing-commit conn
-                                                     commit-hash)))))
+              (with-resource-from-pool (connection-pool) conn
+                (git-repositories-containing-commit conn
+                                                    commit-hash))))
           (let ((show-next-page?
                  (and (not search-query)
                       (>= (length packages)
@@ -843,14 +794,12 @@
                             packages))))
                 #:extra-headers http-headers-for-unchanging-content))
               (else
-               (letpar&
-                   ((locale-options
-                     (with-thread-postgresql-connection
-                      (lambda (conn)
+               (let ((locale-options
+                      (with-resource-from-pool (connection-pool) conn
                         (description-and-synopsis-locale-options
                          (package-description-and-synopsis-locale-options-guix-revision
                           conn
-                          (commit->revision-id conn commit-hash)))))))
+                          (commit->revision-id conn commit-hash))))))
                  (render-html
                   #:sxml (view-revision-packages commit-hash
                                                  query-parameters
@@ -874,19 +823,17 @@
                                                             (header-text
                                                              `("Revision " (samp ,commit-hash))))
   (letpar& ((package-synopsis-counts
-             (with-thread-postgresql-connection
-              (lambda (conn)
-                (synopsis-counts-by-locale conn
-                                           (commit->revision-id
-                                            conn
-                                            commit-hash)))))
+             (with-resource-from-pool (connection-pool) conn
+               (synopsis-counts-by-locale conn
+                                          (commit->revision-id
+                                           conn
+                                           commit-hash))))
             (package-description-counts
-             (with-thread-postgresql-connection
-              (lambda (conn)
-                (description-counts-by-locale conn
-                                              (commit->revision-id
-                                               conn
-                                               commit-hash))))))
+             (with-resource-from-pool (connection-pool) conn
+               (description-counts-by-locale conn
+                                             (commit->revision-id
+                                              conn
+                                              commit-hash)))))
     (case (most-appropriate-mime-type
            '(application/json text/html)
            mime-types)
@@ -916,16 +863,14 @@
                                    (string-append
                                     "/revision/" commit-hash)))
   (letpar& ((package-versions
-             (with-thread-postgresql-connection
-              (lambda (conn)
-                (select-package-versions-for-revision conn
-                                                      commit-hash
-                                                      name))))
+             (with-resource-from-pool (connection-pool) conn
+               (select-package-versions-for-revision conn
+                                                     commit-hash
+                                                     name)))
             (git-repositories-and-branches
-             (with-thread-postgresql-connection
-              (lambda (conn)
-                (git-branches-with-repository-details-for-commit conn
-                                                                 commit-hash)))))
+             (with-resource-from-pool (connection-pool) conn
+               (git-branches-with-repository-details-for-commit conn
+                                                                commit-hash))))
     (case (most-appropriate-mime-type
            '(application/json text/html)
            mime-types)
@@ -963,48 +908,42 @@
      (match-lambda
        ((locale)
         locale))
-     (parallel-via-thread-pool-channel
-      (with-thread-postgresql-connection
-       (lambda (conn)
-         (delete-duplicates
-          (append
-           (package-description-and-synopsis-locale-options-guix-revision
-            conn (commit->revision-id conn commit-hash))
-           (lint-warning-message-locales-for-revision conn commit-hash))))))))
+     (with-resource-from-pool (connection-pool) conn
+       (delete-duplicates
+        (append
+         (package-description-and-synopsis-locale-options-guix-revision
+          conn (commit->revision-id conn commit-hash))
+         (lint-warning-message-locales-for-revision conn commit-hash))))))
 
   (define locale (assq-ref query-parameters 'locale))
 
   (letpar& ((metadata
-             (with-thread-postgresql-connection
-              (lambda (conn)
-                (select-package-metadata-by-revision-name-and-version
-                 conn
-                 commit-hash
-                 name
-                 version
-                 locale))))
+             (with-resource-from-pool (connection-pool) conn
+               (select-package-metadata-by-revision-name-and-version
+                conn
+                commit-hash
+                name
+                version
+                locale)))
             (derivations
-             (with-thread-postgresql-connection
-              (lambda (conn)
-                (select-derivations-by-revision-name-and-version
-                 conn
-                 commit-hash
-                 name
-                 version))))
+             (with-resource-from-pool (connection-pool) conn
+               (select-derivations-by-revision-name-and-version
+                conn
+                commit-hash
+                name
+                version)))
             (git-repositories
-             (with-thread-postgresql-connection
-              (lambda (conn)
-                (git-repositories-containing-commit conn
-                                                    commit-hash))))
+             (with-resource-from-pool (connection-pool) conn
+               (git-repositories-containing-commit conn
+                                                   commit-hash)))
             (lint-warnings
-             (with-thread-postgresql-connection
-              (lambda (conn)
-                (select-lint-warnings-by-revision-package-name-and-version
-                 conn
-                 commit-hash
-                 name
-                 version
-                 #:locale locale)))))
+             (with-resource-from-pool (connection-pool) conn
+               (select-lint-warnings-by-revision-package-name-and-version
+                conn
+                commit-hash
+                name
+                version
+                #:locale locale))))
     (case (most-appropriate-mime-type
            '(application/json text/html)
            mime-types)
@@ -1062,9 +1001,11 @@
           `((error . "invalid query"))))
         (else
          (letpar& ((systems
-                    (with-thread-postgresql-connection list-systems))
+                    (call-with-resource-from-pool (connection-pool)
+                      list-systems))
                    (targets
-                    (with-thread-postgresql-connection valid-targets)))
+                    (call-with-resource-from-pool (connection-pool)
+                      valid-targets)))
            (render-html
             #:sxml (view-revision-package-derivations commit-hash
                                                       query-parameters
@@ -1087,46 +1028,45 @@
              (assq-ref query-parameters 'field)))
         (letpar&
             ((derivations
-              (with-thread-postgresql-connection
-               (lambda (conn)
-                 (if search-query
-                     (search-package-derivations-in-revision
-                      conn
-                      commit-hash
-                      search-query
-                      #:systems (assq-ref query-parameters 'system)
-                      #:targets (assq-ref query-parameters 'target)
-                      #:maximum-builds (assq-ref query-parameters 'maximum_builds)
-                      #:minimum-builds (assq-ref query-parameters 'minimum_builds)
-                      #:build-from-build-servers (assq-ref query-parameters
-                                                           'build_from_build_server)
-                      #:no-build-from-build-servers (assq-ref query-parameters
-                                                              'no_build_from_build_server)
-                      #:build-status (and=> (assq-ref query-parameters
-                                                      'build_status)
-                                            string->symbol)
-                      #:limit-results limit-results
-                      #:after-name (assq-ref query-parameters 'after_name)
-                      #:include-builds? (member "builds" fields))
-                     (select-package-derivations-in-revision
-                      conn
-                      commit-hash
-                      #:systems (assq-ref query-parameters 'system)
-                      #:targets (assq-ref query-parameters 'target)
-                      #:maximum-builds (assq-ref query-parameters 'maximum_builds)
-                      #:minimum-builds (assq-ref query-parameters 'minimum_builds)
-                      #:build-from-build-servers (assq-ref query-parameters
-                                                           'build_from_build_server)
-                      #:no-build-from-build-servers (assq-ref query-parameters
-                                                              'no_build_from_build_server)
-                      #:build-status (and=> (assq-ref query-parameters
-                                                      'build_status)
-                                            string->symbol)
-                      #:limit-results limit-results
-                      #:after-name (assq-ref query-parameters 'after_name)
-                      #:include-builds? (member "builds" fields))))))
+              (with-resource-from-pool (connection-pool) conn
+                (if search-query
+                    (search-package-derivations-in-revision
+                     conn
+                     commit-hash
+                     search-query
+                     #:systems (assq-ref query-parameters 'system)
+                     #:targets (assq-ref query-parameters 'target)
+                     #:maximum-builds (assq-ref query-parameters 'maximum_builds)
+                     #:minimum-builds (assq-ref query-parameters 'minimum_builds)
+                     #:build-from-build-servers (assq-ref query-parameters
+                                                          'build_from_build_server)
+                     #:no-build-from-build-servers (assq-ref query-parameters
+                                                             'no_build_from_build_server)
+                     #:build-status (and=> (assq-ref query-parameters
+                                                     'build_status)
+                                           string->symbol)
+                     #:limit-results limit-results
+                     #:after-name (assq-ref query-parameters 'after_name)
+                     #:include-builds? (member "builds" fields))
+                    (select-package-derivations-in-revision
+                     conn
+                     commit-hash
+                     #:systems (assq-ref query-parameters 'system)
+                     #:targets (assq-ref query-parameters 'target)
+                     #:maximum-builds (assq-ref query-parameters 'maximum_builds)
+                     #:minimum-builds (assq-ref query-parameters 'minimum_builds)
+                     #:build-from-build-servers (assq-ref query-parameters
+                                                          'build_from_build_server)
+                     #:no-build-from-build-servers (assq-ref query-parameters
+                                                             'no_build_from_build_server)
+                     #:build-status (and=> (assq-ref query-parameters
+                                                     'build_status)
+                                           string->symbol)
+                     #:limit-results limit-results
+                     #:after-name (assq-ref query-parameters 'after_name)
+                     #:include-builds? (member "builds" fields)))))
              (build-server-urls
-              (with-thread-postgresql-connection
+              (with-resource-from-pool (connection-pool) conn
                select-build-server-urls-by-id)))
           (let ((show-next-page?
                  (if all-results
@@ -1161,9 +1101,11 @@
                                         derivations))))))
               (else
                (letpar& ((systems
-                          (with-thread-postgresql-connection list-systems))
+                          (call-with-resource-from-pool (connection-pool)
+                            list-systems))
                          (targets
-                          (with-thread-postgresql-connection valid-targets)))
+                          (call-with-resource-from-pool (connection-pool)
+                            valid-targets)))
                  (render-html
                   #:sxml (view-revision-package-derivations
                           commit-hash
@@ -1197,9 +1139,11 @@
           `((error . "invalid query"))))
         (else
          (letpar& ((systems
-                    (with-thread-postgresql-connection list-systems))
+                    (call-with-resource-from-pool (connection-pool)
+                      list-systems))
                    (targets
-                    (with-thread-postgresql-connection valid-targets)))
+                    (call-with-resource-from-pool (connection-pool)
+                      valid-targets)))
            (render-html
             #:sxml (view-revision-fixed-output-package-derivations
                     commit-hash
@@ -1222,20 +1166,19 @@
              (assq-ref query-parameters 'field)))
         (letpar&
             ((derivations
-              (with-thread-postgresql-connection
-               (lambda (conn)
-                 (select-fixed-output-package-derivations-in-revision
-                  conn
-                  commit-hash
-                  (assq-ref query-parameters 'system)
-                  (assq-ref query-parameters 'target)
-                  #:latest-build-status (assq-ref query-parameters
-                                                  'latest_build_status)
-                  #:limit-results limit-results
-                  #:after-derivation-file-name
-                  (assq-ref query-parameters 'after_name)))))
+              (with-resource-from-pool (connection-pool) conn
+                (select-fixed-output-package-derivations-in-revision
+                 conn
+                 commit-hash
+                 (assq-ref query-parameters 'system)
+                 (assq-ref query-parameters 'target)
+                 #:latest-build-status (assq-ref query-parameters
+                                                 'latest_build_status)
+                 #:limit-results limit-results
+                 #:after-derivation-file-name
+                 (assq-ref query-parameters 'after_name))))
              (build-server-urls
-              (with-thread-postgresql-connection
+              (with-resource-from-pool (connection-pool) conn
                select-build-server-urls-by-id)))
           (let ((show-next-page?
                  (if all-results
@@ -1251,9 +1194,11 @@
                 `((derivations . ,(list->vector derivations)))))
               (else
                (letpar& ((systems
-                          (with-thread-postgresql-connection list-systems))
+                          (call-with-resource-from-pool (connection-pool)
+                            list-systems))
                          (targets
-                          (with-thread-postgresql-connection valid-targets)))
+                          (call-with-resource-from-pool (connection-pool)
+                            valid-targets)))
                  (render-html
                   #:sxml (view-revision-fixed-output-package-derivations
                           commit-hash
@@ -1278,8 +1223,9 @@
           (header-link
            (string-append "/revision/" commit-hash)))
   (define build-server-urls
-    (parallel-via-thread-pool-channel
-     (with-thread-postgresql-connection select-build-server-urls-by-id)))
+    (call-with-resource-from-pool
+     (connection-pool)
+     select-build-server-urls-by-id))
 
   (if (any-invalid-query-parameters? query-parameters)
       (case (most-appropriate-mime-type
@@ -1290,9 +1236,11 @@
           `((error . "invalid query"))))
         (else
          (letpar& ((systems
-                    (with-thread-postgresql-connection list-systems))
+                    (call-with-resource-from-pool (connection-pool)
+                      list-systems))
                    (targets
-                    (with-thread-postgresql-connection valid-targets)))
+                    (call-with-resource-from-pool (connection-pool)
+                      valid-targets)))
            (render-html
             #:sxml (view-revision-package-derivation-outputs
                     commit-hash
@@ -1313,23 +1261,22 @@
              (assq-ref query-parameters 'field)))
         (letpar&
             ((derivation-outputs
-              (with-thread-postgresql-connection
-               (lambda (conn)
-                 (select-derivation-outputs-in-revision
-                  conn
-                  commit-hash
-                  #:search-query (assq-ref query-parameters 'search_query)
-                  #:nars-from-build-servers
-                  (assq-ref query-parameters 'substitutes_available_from)
-                  #:no-nars-from-build-servers
-                  (assq-ref query-parameters 'substitutes_not_available_from)
-                  #:output-consistency
-                  (assq-ref query-parameters 'output_consistency)
-                  #:system (assq-ref query-parameters 'system)
-                  #:target (assq-ref query-parameters 'target)
-                  #:include-nars? (member "nars" fields)
-                  #:limit-results limit-results
-                  #:after-path (assq-ref query-parameters 'after_path))))))
+              (with-resource-from-pool (connection-pool) conn
+                (select-derivation-outputs-in-revision
+                 conn
+                 commit-hash
+                 #:search-query (assq-ref query-parameters 'search_query)
+                 #:nars-from-build-servers
+                 (assq-ref query-parameters 'substitutes_available_from)
+                 #:no-nars-from-build-servers
+                 (assq-ref query-parameters 'substitutes_not_available_from)
+                 #:output-consistency
+                 (assq-ref query-parameters 'output_consistency)
+                 #:system (assq-ref query-parameters 'system)
+                 #:target (assq-ref query-parameters 'target)
+                 #:include-nars? (member "nars" fields)
+                 #:limit-results limit-results
+                 #:after-path (assq-ref query-parameters 'after_path)))))
           (let ((show-next-page?
                  (if all-results
                      #f
@@ -1395,9 +1342,11 @@
                             derivation-outputs))))))
               (else
                (letpar& ((systems
-                          (with-thread-postgresql-connection list-systems))
+                          (call-with-resource-from-pool (connection-pool)
+                            list-systems))
                          (targets
-                          (with-thread-postgresql-connection valid-targets)))
+                          (call-with-resource-from-pool (connection-pool)
+                            valid-targets)))
                  (render-html
                   #:sxml (view-revision-package-derivation-outputs
                           commit-hash
@@ -1422,9 +1371,11 @@
                                   (string-append "/revision/" commit-hash)))
   (if (any-invalid-query-parameters? query-parameters)
       (letpar& ((systems
-                 (with-thread-postgresql-connection list-systems))
+                 (call-with-resource-from-pool (connection-pool)
+                   list-systems))
                 (targets
-                 (with-thread-postgresql-connection valid-targets)))
+                 (call-with-resource-from-pool (connection-pool)
+                   valid-targets)))
         (render-html
          #:sxml
          (view-revision-builds query-parameters
@@ -1438,41 +1389,40 @@
       (let ((system (assq-ref query-parameters 'system))
             (target (assq-ref query-parameters 'target)))
         (letpar& ((systems
-                   (with-thread-postgresql-connection list-systems))
+                   (call-with-resource-from-pool (connection-pool)
+                     list-systems))
                   (targets
-                   (with-thread-postgresql-connection valid-targets))
+                   (call-with-resource-from-pool (connection-pool)
+                     valid-targets))
                   (build-server-options
-                   (with-thread-postgresql-connection
-                    (lambda (conn)
-                      (map (match-lambda
-                             ((id url lookup-all-derivations
-                                  lookup-builds)
-                              (cons url id)))
-                           (select-build-servers conn)))))
+                   (with-resource-from-pool (connection-pool) conn
+                     (map (match-lambda
+                            ((id url lookup-all-derivations
+                                 lookup-builds)
+                             (cons url id)))
+                          (select-build-servers conn))))
                   (stats
-                   (with-thread-postgresql-connection
-                    (lambda (conn)
-                      (select-build-stats
-                       conn
-                       (assq-ref query-parameters
-                                 'build_server)
-                       #:revision-commit commit-hash
-                       #:system system
-                       #:target target))))
+                   (with-resource-from-pool (connection-pool) conn
+                     (select-build-stats
+                      conn
+                      (assq-ref query-parameters
+                                'build_server)
+                      #:revision-commit commit-hash
+                      #:system system
+                      #:target target)))
                   (builds
-                   (with-thread-postgresql-connection
-                    (lambda (conn)
-                      (select-builds-with-context
-                       conn
-                       (assq-ref query-parameters
-                                 'build_status)
-                       (assq-ref query-parameters
-                                 'build_server)
-                       #:revision-commit commit-hash
-                       #:system system
-                       #:target target
-                       #:limit (assq-ref query-parameters
-                                         'limit_results))))))
+                   (with-resource-from-pool (connection-pool) conn
+                     (select-builds-with-context
+                      conn
+                      (assq-ref query-parameters
+                                'build_status)
+                      (assq-ref query-parameters
+                                'build_server)
+                      #:revision-commit commit-hash
+                      #:system system
+                      #:target target
+                      #:limit (assq-ref query-parameters
+                                        'limit_results)))))
           (render-html
            #:sxml (view-revision-builds query-parameters
                                         commit-hash
@@ -1494,9 +1444,11 @@
                                           (string-append "/revision/" commit-hash)))
   (if (any-invalid-query-parameters? query-parameters)
       (letpar& ((systems
-                 (with-thread-postgresql-connection list-systems))
+                 (call-with-resource-from-pool (connection-pool)
+                   list-systems))
                 (targets
-                 (with-thread-postgresql-connection valid-targets)))
+                 (call-with-resource-from-pool (connection-pool)
+                   valid-targets)))
         (render-html
          #:sxml
          (view-revision-blocking-builds query-parameters
@@ -1509,29 +1461,29 @@
       (let ((system (assq-ref query-parameters 'system))
             (target (assq-ref query-parameters 'target)))
         (letpar& ((systems
-                   (with-thread-postgresql-connection list-systems))
+                   (call-with-resource-from-pool (connection-pool)
+                     list-systems))
                   (targets
-                   (with-thread-postgresql-connection valid-targets))
+                   (call-with-resource-from-pool (connection-pool)
+                     valid-targets))
                   (build-server-options
-                   (with-thread-postgresql-connection
-                    (lambda (conn)
-                      (map (match-lambda
-                             ((id url lookup-all-derivations
-                                  lookup-builds)
-                              (cons url id)))
-                           (select-build-servers conn)))))
+                   (with-resource-from-pool (connection-pool) conn
+                     (map (match-lambda
+                            ((id url lookup-all-derivations
+                                 lookup-builds)
+                             (cons url id)))
+                          (select-build-servers conn))))
                   (blocking-builds
-                   (with-thread-postgresql-connection
-                    (lambda (conn)
-                      (select-blocking-builds
-                       conn
-                       commit-hash
-                       #:build-server-ids
-                       (assq-ref query-parameters 'build_server)
-                       #:system system
-                       #:target target
-                       #:limit (assq-ref query-parameters
-                                         'limit_results))))))
+                   (with-resource-from-pool (connection-pool) conn
+                     (select-blocking-builds
+                      conn
+                      commit-hash
+                      #:build-server-ids
+                      (assq-ref query-parameters 'build_server)
+                      #:system system
+                      #:target target
+                      #:limit (assq-ref query-parameters
+                                        'limit_results)))))
           (render-html
            #:sxml (view-revision-blocking-builds query-parameters
                                                  commit-hash
@@ -1551,24 +1503,20 @@
                                         (header-link
                                          (string-append "/revision/" commit-hash)))
   (define lint-checker-options
-    (parallel-via-thread-pool-channel
-     (with-thread-postgresql-connection
-      (lambda (conn)
-        (map (match-lambda
-               ((name description network-dependent)
-                (cons (string-append name ": " description )
-                      name)))
-             (lint-checkers-for-revision conn commit-hash))))))
+    (with-resource-from-pool (connection-pool) conn
+      (map (match-lambda
+             ((name description network-dependent)
+              (cons (string-append name ": " description )
+                    name)))
+           (lint-checkers-for-revision conn commit-hash))))
 
   (define lint-warnings-locale-options
-    (parallel-via-thread-pool-channel
-     (with-thread-postgresql-connection
-      (lambda (conn)
-        (map
-         (match-lambda
-           ((locale)
-            locale))
-         (lint-warning-message-locales-for-revision conn commit-hash))))))
+    (with-resource-from-pool (connection-pool) conn
+      (map
+       (match-lambda
+         ((locale)
+          locale))
+       (lint-warning-message-locales-for-revision conn commit-hash))))
 
   (if (any-invalid-query-parameters? query-parameters)
       (case (most-appropriate-mime-type
@@ -1597,18 +1545,16 @@
             (fields (assq-ref query-parameters 'field)))
         (letpar&
             ((git-repositories
-              (with-thread-postgresql-connection
-               (lambda (conn)
-                 (git-repositories-containing-commit conn
-                                                     commit-hash))))
+              (with-resource-from-pool (connection-pool) conn
+                (git-repositories-containing-commit conn
+                                                    commit-hash)))
              (lint-warnings
-              (with-thread-postgresql-connection
-               (lambda (conn)
-                 (lint-warnings-for-guix-revision conn commit-hash
-                                                  #:locale locale
-                                                  #:package-query package-query
-                                                  #:linters linters
-                                                  #:message-query message-query)))))
+              (with-resource-from-pool (connection-pool) conn
+                (lint-warnings-for-guix-revision conn commit-hash
+                                                 #:locale locale
+                                                 #:package-query package-query
+                                                 #:linters linters
+                                                 #:message-query message-query))))
           (let ((any-translated-lint-warnings?
                  (any-translated-lint-warnings? lint-warnings locale)))
             (case (most-appropriate-mime-type