On Tue, 2010-02-02 at 18:48 -0700, hj lee wrote:
>
>
> getenv() and setenv() are not required by posix to be thread
> safe (see
> man pthreads). I assume there is a good reason for this.
>
> >From my interpretation of that man page, it appears syslog()
> is required
> to be thread safe. I took a look at glibc2.9 and it does
> indeed use
> strftime_l inside its syslog calls (which is on the
> non-threadsafe
> list).
>
> One workaround is simply to remove the use of the syslog libc
> API and
> implement it directly. I am not too enthusiastic about the
> current
> syslog implementation in libc after reading through the code
> (memory
> allocations, etc). This was done in the past but at some
> point was
> reverted.
>
> The issue remains regarding the proper use of getenv() and
> setenv()
> inside corosync. Ideally we wouldn't use thread unsafe apis,
> but we do
> and getenv/setenv seem pretty important. I thought of using
> weak (or
> maybe its called lazy) bindings to override getenv and setenv,
> but these
> apis appear to not support lazy(/or weak i forget term)
> bindings.
>
> To correct this problem fully I suggest the following changes:
> 1) write our own syslog implementation which connects to the
> syslog
> daemon socket and uses the write system call to write the
> output.
> Examples of this are in older versions of openais
> 2) add getenv() and setenv() apis to the coroapi definitions
> these getenv/setenv call the libc getenv/setenv with a mutex
> held to
> mutually exclude the environment. Pacemaker and internal
> corosync code
> can then call these getenv/setenv calls where necessary to
> ensure
> correct operation.
>
> There may be some issue with pacemaker using setenv after
> forking which
> could then operate on an invalid mutex that I would like
> Andrew's
> feedback regarding.
>
> bzs:
>
> https://bugzilla.redhat.com/show_bug.cgi?id=561180
>
> https://bugzilla.redhat.com/show_bug.cgi?id=561181
>
> Feel free to add your analysis
>
> Regards
> -steve
>
> Thank you very much. I added a test program and some comments on
> bugzilla. Also I tested my two proposals since I need some fix right
> now. It worked OK. Only thing I needed to export
> HA_cluster_type=openais. I added this to /etc/init.d/corosync before
> start(). I could change the pacemaker source to use openais by default
> if HA_cluster_type is not set, then I don't need to export. But it's
> OK. Until the fix is available, I will use my workaround.
>
> hj
Would you please test the attached fix. It should provide a workaround.
Regards
-steve
Index: exec/main.c
===================================================================
--- exec/main.c (revision 2651)
+++ exec/main.c (working copy)
@@ -1183,6 +1183,14 @@
corosync_totem_stats_init ();
}
+/*
+ * Work around syslog lack of thread safety because tzset uses getenv()
+ * on linux libc
+ */
+void tzset (void)
+{
+}
+
int main (int argc, char **argv)
{
const char *error_string;
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