Ben Chobot <bench(at)silentmedia(dot)com> writes:
> On Fri, 15 Jan 2010, Tom Lane wrote:
>> Try attaching to the process with gdb and getting a stack trace.
> #0 0x00007f59a5d78ca7 in semop () from /lib/libc.so.6
> #1 0x0000000000546656 in PGSemaphoreLock ()
> #2 0x00000000005618ee in LockBufferForCleanup ()
> #3 0x000000000045c8e2 in btbulkdelete ()
OK, so it's trying to get an exclusive page-level lock on some page of
the index. The only thing that could block that for any long period is
if some other process is sitting with an open indexscan. Look around
for processes that have been "idle in transaction" for a long time ...
regards, tom lane