Re: BUG #16685: The ecpg thread/descriptor test fails sometimes on Windows - Mailing list pgsql-bugs

From Tom Lane
Subject Re: BUG #16685: The ecpg thread/descriptor test fails sometimes on Windows
Date
Msg-id 367782.1603554604@sss.pgh.pa.us
Whole thread Raw
In response to BUG #16685: The ecpg thread/descriptor test fails sometimes on Windows  (PG Bug reporting form <noreply@postgresql.org>)
Responses Re: BUG #16685: The ecpg thread/descriptor test fails sometimes on Windows  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-bugs
PG Bug reporting form <noreply@postgresql.org> writes:
> I found that the get_descriptors() function called in ECPGdeallocate_desc
> sometimes can return null.

> The following debugging code inserted into the ECPGallocate_desc:
> ...
> shows on a failure:
> TlsGetValue() returned null on iteration 209, error: 0, descriptor_key: 28,
> initial descriptor_key: 0.
> or
> TlsGetValue() returned null on iteration: 369, error: 0, descriptor_key: 28,
> initial descriptor_key: 0

Hm.  I'm supposing that 0 isn't likely to be the correct TLS index,
and what this is showing us is that we got here before anyone had
done descriptor_key_init.

I'll bet that the correct fix is

 static void
 set_descriptors(struct descriptor *value)
 {
+    pthread_once(&descriptor_once, descriptor_key_init);
    pthread_setspecific(descriptor_key, value);
 }

and that you could probably reproduce this on non-Windows, too,
if you tried hard (sticking a delay in get_descriptors might do it).

            regards, tom lane



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