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| author | Joey Hess <joey@kitenet.net> | 2012-10-09 17:03:52 -0400 |
|---|---|---|
| committer | Joey Hess <joey@kitenet.net> | 2012-10-09 17:12:04 -0400 |
| commit | 6bd8c6732e7ccda0013a3373c3618fca91c91d36 (patch) | |
| tree | e4677c50f7b3cf805cb352c39623af3bcb0cb3f5 | |
| parent | 4c1582c11eb85bf356c943abf1b31dde3453e73d (diff) | |
| download | ikiwiki-6bd8c6732e7ccda0013a3373c3618fca91c91d36.tar ikiwiki-6bd8c6732e7ccda0013a3373c3618fca91c91d36.tar.gz | |
add cgi_overload_delay tunable
Try to avoid a situation in which so many ikiwiki cgi wrapper programs are
running, all waiting on some long-running thing like a site rebuild, that
it prevents the web server from doing anything else. The current approach
only avoids this problem for GET requests; if multiple cgi's run GETs on a
site at the same time, one will display a "please wait" page for a
configurable number of seconds, which then redirects to retry. To enable
this protection, set cgi_overload_delay to the number of seconds to wait.
This is not enabled by default.
| -rw-r--r-- | IkiWiki.pm | 8 | ||||
| -rw-r--r-- | IkiWiki/Wrapper.pm | 47 | ||||
| -rw-r--r-- | debian/changelog | 8 |
3 files changed, 58 insertions, 5 deletions
diff --git a/IkiWiki.pm b/IkiWiki.pm index f68797ae3..a7dc6b36b 100644 --- a/IkiWiki.pm +++ b/IkiWiki.pm @@ -118,6 +118,14 @@ sub getsetup () { safe => 0, rebuild => 0, }, + cgi_overload_delay => { + type => "string", + default => '', + example => "10", + description => "number of seconds to delay CGI requests when overloaded", + safe => 1, + rebuild => 0, + }, rcs => { type => "string", default => '', diff --git a/IkiWiki/Wrapper.pm b/IkiWiki/Wrapper.pm index 769540d29..0855a3ba2 100644 --- a/IkiWiki/Wrapper.pm +++ b/IkiWiki/Wrapper.pm @@ -93,12 +93,43 @@ EOF # memory, a pile up of processes could cause thrashing # otherwise. The fd of the lock is stored in # IKIWIKI_CGILOCK_FD so unlockwiki can close it. - $pre_exec=<<"EOF"; + # + # A lot of cgi wrapper processes can potentially build + # up and clog an otherwise unloaded web server. To + # partially avoid this, when a GET comes in and the lock + # is already held, rather than blocking a html page is + # constructed that retries. This is enabled by setting + # cgi_overload_delay. + if (defined $config{cgi_overload_delay} && + $config{cgi_overload_delay} =~/^[0-9]+/) { + my $i=int($config{cgi_overload_delay}); + $pre_exec.="#define CGI_OVERLOAD_DELAY $i\n" + if $i > 0; + } + $pre_exec.=<<"EOF"; lockfd=open("$config{wikistatedir}/cgilock", O_CREAT | O_RDWR, 0666); - if (lockfd != -1 && lockf(lockfd, F_LOCK, 0) == 0) { - char *fd_s=malloc(8); - sprintf(fd_s, "%i", lockfd); - setenv("IKIWIKI_CGILOCK_FD", fd_s, 1); + if (lockfd != -1) { +#ifdef CGI_OVERLOAD_DELAY + char *request_method = getenv("REQUEST_METHOD"); + if (request_method && strcmp(request_method, "GET") == 0) { + if (lockf(lockfd, F_TLOCK, 0) == 0) { + set_cgilock_fd(lockfd); + } + else { + printf("Content-Type: text/html\\nRefresh: %i; URL=%s\\n\\n<html><head><title>please wait...</title><head><body><p>Please wait ...</p></body></html>", + CGI_OVERLOAD_DELAY, + getenv("REQUEST_URI")); + exit(0); + } + } + else if (lockf(lockfd, F_LOCK, 0) == 0) { + set_cgilock_fd(lockfd); + } +#else + if (lockf(lockfd, F_LOCK, 0) == 0) { + set_cgilock_fd(lockfd); + } +#endif } EOF } @@ -140,6 +171,12 @@ void addenv(char *var, char *val) { newenviron[i++]=s; } +set_cgilock_fd (int lockfd) { + char *fd_s=malloc(8); + sprintf(fd_s, "%i", lockfd); + setenv("IKIWIKI_CGILOCK_FD", fd_s, 1); +} + int main (int argc, char **argv) { int lockfd=-1; char *s; diff --git a/debian/changelog b/debian/changelog index 8d7618753..842eb6806 100644 --- a/debian/changelog +++ b/debian/changelog @@ -3,6 +3,14 @@ ikiwiki (3.20120726) UNRELEASED; urgency=low * monochrome: New theme, contributed by Jon Dowland. * rst: Ported to python 3, while still also being valid python 2. Thanks, W. Trevor King + * Try to avoid a situation in which so many ikiwiki cgi wrapper programs + are running, all waiting on some long-running thing like a site rebuild, + that it prevents the web server from doing anything else. The current + approach only avoids this problem for GET requests; if multiple cgi's + run GETs on a site at the same time, one will display a "please wait" + page for a configurable number of seconds, which then redirects to retry. + To enable this protection, set cgi_overload_delay to the number of + seconds to wait. This is not enabled by default. -- Joey Hess <joeyh@debian.org> Thu, 30 Aug 2012 11:56:12 -0400 |