Postgres DB crashing

Hello,
Greetings. 
My PostgresSQL (9.2) is crashing after certain load tests. Currently, postgressql is crashing when simulatenously 800 to 1000 threads are run on a 10 million records schema. Not sure, if we have to tweak some more parameters of postgres. Currently, the postgressql is configured as below on a 7GB Ram on an Intel Xeon CPU E5507 2.27 GZ. Is this postgres limitation to support only 800 threads or any other configuration required. Please look at the log as below with errors. Please reply
 
 


 
 
 
  max_connections 
  5000
 
 
  shared_buffers 
  2024 MB
 
 
  synchronous_commit
  off
 
 
  wal_buffers
  100 MB
 
 
  wal_writer_delays
  1000ms
 
 
  checkpoint_segments
  512
 
 
  checkpoint_timeout
  5 min
 
 
  checkpoint_completion_target
  0.5
 
 
  checkpoint_warning
  30s
 
 
  work_memory
  1G
 
 
  effective_cache_size
  5 GB
 

 
 
 
2013-06-11 15:11:17 GMT [26201]: [1-1]ERROR:  canceling autovacuum task


2013-06-11 15:11:17 GMT [26201]: [2-1]CONTEXT:  automatic vacuum of table "newrelic.tenant1.customer"


2013-06-11 15:11:17 GMT [25242]: [1-1]LOG:  sending cancel to blocking autovacuum PID 26201


2013-06-11 15:11:17 GMT [25242]: [2-1]DETAIL:  Process 25242 waits for ExclusiveLock on extension of relation 679054 of database 666546.


2013-06-11 15:11:17 GMT [25242]: [3-1]STATEMENT:  UPDATE tenant1.customer SET lastmodifieddate = $1 WHERE id IN ( select random_range((select min(id) from tenant1.customer ), (select max(id) from tenant1.customer )) as id ) AND softdeleteflag IS NOT TRUE


2013-06-11 15:11:17 GMT [25242]: [4-1]WARNING:  could not send signal to process 26201: No such process


2013-06-11 15:22:29 GMT [22229]: [11-1]WARNING:  worker took too long to start; canceled


2013-06-11 15:24:10 GMT [26511]: [1-1]WARNING:  autovacuum worker started without a worker entry


2013-06-11 16:03:33 GMT [23092]: [1-1]LOG:  could not receive data from client: Connection timed out


2013-06-11 16:06:05 GMT [23222]: [5-1]LOG:  could not receive data from client: Connection timed out


2013-06-11 16:07:06 GMT [26869]: [1-1]FATAL:  canceling authentication due to timeout


2013-06-11 16:23:16 GMT [25128]: [1-1]LOG:  could not receive data from client: Connection timed out


2013-06-11 16:23:20 GMT [25128]: [2-1]LOG:  unexpected EOF on client connection with an open transaction


2013-06-11 16:30:56 GMT [23695]: [1-1]LOG:  could not receive data from client: Connection timed out


2013-06-11 16:43:55 GMT [24618]: [1-1]LOG:  could not receive data from client: Connection timed out


2013-06-11 16:44:29 GMT [25204]: [1-1]LOG:  could not receive data from client: Connection timed out


2013-06-11 16:54:14 GMT [22226]: [1-1]PANIC:  stuck spinlock (0x2aaab54279d4) detected at bufmgr.c:1239


2013-06-11 16:54:14 GMT [32521]: [8-1]LOG:  checkpointer process (PID 22226) was terminated by signal 6: Aborted


2013-06-11 16:54:14 GMT [32521]: [9-1]LOG:  terminating any other active server processes


2013-06-11 16:54:14 GMT [26931]: [1-1]WARNING:  terminating connection because of crash of another server process


2013-06-11 16:54:14 GMT [26931]: [2-1]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.


2013-06-11 16:54:14 GMT [26931]: [3-1]HINT:  In a moment you should be able to reconnect to the database and repeat your command.


2013-06-11 16:54:14 GMT [26401]: [1-1]WARNING:  terminating connection because of crash of another server process


2013-06-11 16:54:14 GMT [26401]: [2-1]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.
 
2013-06-11 16:55:08 GMT [27579]: [1-1]FATAL:  the database system is in recovery mode


2013-06-11 16:55:08 GMT [24041]: [1-1]WARNING:  terminating connection because of crash of another server process


2013-06-11 16:55:08 GMT [24041]: [2-1]DETAIL:  The postmaster has commanded this server process to roll back the current