LOG: statistics buffer is full

Hello,

        We use 7.4.6 version and now we have a bad performance on our
production server. We detected several strange messages in a log file :

    LOG:  statistics buffer is full
    LOG:  statistics buffer is full
    LOG:  statistics buffer is full

When i search on mailings list archive, i found a patch to increase the
buffer size in src/include/pgstat.h

-#define PGSTAT_RECVBUFFERSZ ((int) (1024 * sizeof(PgStat_Msg)))
+#define PGSTAT_RECVBUFFERSZ ((int) (16384 * sizeof(PgStat_Msg)))

And when i look the same file on the subversion trunk, the
"PGSTAT_RECVBUFFERSZ" constant is defined in a new file :
src/backend/postmaster/pgstat.c but with a same value.

Can you explain this statistics buffer problem ? And increase this
buffer size is a good resolution ?

Thanks for your help

Best Regards,
Jérôme BENOIS.
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