problem with locks on head, backend crash

Hello

when I tested ptop, I found some problems

this pgbench is very slow and when after getting table of locks from
ptop I got backend crash.

[pavel@prg31 ~]$ /usr/local/pgsql/bin/pgbench -c80 -t1000 postgres
starting vacuum...end.
WARNING:  you don't own a lock of type ShareLock
WARNING:  you don't own a lock of type ShareLock
WARNING:  terminating connection because of crash of another server process
DETAIL:  The postmaster has commanded this server process to roll back
the current transaction and exit, because another server process
exited abnormally and possibly corrupted shared memory.
HINT:  In a moment you should be able to reconnect to the database and
repeat your command.
WARNING:  terminating connection because of crash of another server process
DETAIL:  The postmaster has commanded this server process to roll back
the current transaction and exit, because another server process
exited abnormally and possibly corrupted shared memory.

from log:

LOG:  unexpected EOF on client connection
LOG:  could not send data to client: Přerušena roura (SIGPIPE)
LOG:  unexpected EOF on client connection
LOG:  could not send data to client: Přerušena roura (SIGPIPE)
LOG:  unexpected EOF on client connection
WARNING:  problem in alloc set MessageContext: req size > alloc size
for chunk 0x8b6d1e0 in block 0x8b6bb50
WARNING:  problem in alloc set MessageContext: req size > alloc size
for chunk 0x8b6d1e0 in block 0x8b6bb50
LOG:  server process (PID 29693) was terminated by signal 11: Segmentation fault
LOG:  terminating any other active server processes
WARNING:  terminating connection because of crash of another server process
DETAIL:  The postmaster has commanded this server process to roll back
the current transaction and exit, because another s
HINT:  In a moment you should be able to reconnect to the database and
repeat your command.
WARNING:  terminating connection because of crash of another server process

Regards
Pavel Stehule