From bb225189fd56d89ec8be926dda269295ccbfe918 Mon Sep 17 00:00:00 2001 From: Christopher Baines Date: Mon, 3 Feb 2020 12:58:22 +0100 Subject: utils: Handle errors in worker threads. Previously, if an error occurred, the worker fiber simply never sends a reply. In the case of HTTP requests to Cuirass, where an exception occurs when performing a database query, the fiber handling the request blocks as it never gets a response. I think that this has the potential to cause the process to hit file descriptor limits, as the connections are never responded to. This is fixed by responding with the details of the exception, and then throwing it within the fiber that made the call. * src/cuirass/utils.scm (make-worker-thread-channel): Catch exceptions when calling proc. (call-with-worker-thread): Handle receiving exceptions from the worker thread. --- src/cuirass/utils.scm | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/src/cuirass/utils.scm b/src/cuirass/utils.scm index f3ba18d..0bcbb35 100644 --- a/src/cuirass/utils.scm +++ b/src/cuirass/utils.scm @@ -114,7 +114,12 @@ arguments of the worker thread procedure." (let loop () (match (get-message channel) (((? channel? reply) . (? procedure? proc)) - (put-message reply (apply proc args)))) + (put-message reply + (catch #t + (lambda () + (apply proc args)) + (lambda (key . args) + (cons* 'worker-thread-error key args)))))) (loop))))))) (iota parallelism)) channel))) @@ -127,7 +132,10 @@ If already in the worker thread, call PROC immediately." (apply proc args) (let ((reply (make-channel))) (put-message channel (cons reply proc)) - (get-message reply))))) + (match (get-message reply) + (('worker-thread-error key args ...) + (apply throw key args)) + (result result)))))) (define-syntax-rule (with-worker-thread channel (vars ...) exp ...) "Evaluate EXP... in the worker thread corresponding to CHANNEL. -- cgit v1.2.3