Martin Blapp wrote:
Hi,
It looks like the codepath in do_multipart() is not threadsafe, as it
deadlocks threads entering it at the same time. This needs more
investigation
but for now this quick fix (the third one) will be enough. Since I use this
patch, CPU utilisation has go down and even a flood of scans recovered
fast.
In opposite, a maginal load of 3-4 mails per second without this patch
leads
to starvation with libpthread.so very soon.
--
Martin
--- libclamav/mbox.c Tue Feb 13 14:06:57 2007
+++ libclamav/mbox.c Sun Mar 11 08:57:56 2007
@@ -413,6 +413,7 @@
#ifdef CL_THREAD_SAFE
static pthread_mutex_t tables_mutex = PTHREAD_MUTEX_INITIALIZER;
+static pthread_mutex_t multipart_mutex = PTHREAD_MUTEX_INITIALIZER;
#endif
#ifndef O_BINARY
@@ -2506,10 +2512,16 @@
case APPLEDOUBLE:
case KNOWBOT:
case -1:
+#ifdef CL_THREAD_SAFE
+ pthread_mutex_lock(&multipart_mutex);
+#endif
mainMessage = do_multipart(mainMessage,
messages, multiparts,
&rc, mctx, messageIn,
&aText, recursion_level);
+#ifdef CL_THREAD_SAFE
+ pthread_mutex_unlock(&multipart_mutex);
+#endif
--multiparts;
if(rc == VIRUS)
infected = TRUE;
@@ -2686,9 +2701,15 @@
cli_dbgmsg("Mixed message with %d parts\n", multiparts);
for(i = 0; i < multiparts; i++) {
+#ifdef CL_THREAD_SAFE
+ pthread_mutex_lock(&multipart_mutex);
+#endif
mainMessage = do_multipart(mainMessage,
messages, i, &rc, mctx,
messageIn, &aText, recursion_level + 1);
+#ifdef CL_THREAD_SAFE
+ pthread_mutex_unlock(&multipart_mutex);
+#endif
if(rc == VIRUS) {
infected = TRUE;
break;
do_multipart() does not spawn multiple threads, or access global variables,
so there is nothing that it needs to be thread-safe for.
Perhaps it is something else that is not thread safe, that do_mulipart() is
calling?
Naturally CPU usage will go down if you change an application from multiple to
single threading,
that does not necessarily indicate a problem, quite the opposite, it could
indicate
that all is working as it should.
Please demonstrate evidence, e.g. files which cause a deadlock when scanned.
Please
also test against SVN, patches are only accepted against that version.
Martin Blapp, <[EMAIL PROTECTED]> <[EMAIL PROTECTED]>
-Nigel
--
Nigel Horne. Arranger, Adjudicator, Band Trainer, Composer, Tutor, Typesetter.
NJH Music, Barnsley, UK. ICQ#20252325
[EMAIL PROTECTED] http://www.bandsman.co.uk
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