top and sar says 100% cpu usage of one core, no sign of I/O wait. The database is 1.5TB in size. RAM in master is 145GB, on slave it's differ, some has about 16GB another has 145GB also.
nothing suspicious on standby's postgres log.
on master's postgres log :
WARNING,01000,"pgstat wait timeout",,,,,,,,,""
ERROR,57014,"canceling autovacuum task",,,,,"automatic vacuum of table ""consprod._consprod_replication.sl_event""",,,,""
ERROR,57014,"canceling statement due to statement timeout",,,,,,"
"PARSE",2014-06-26 00:39:35 CDT,91/0,0,ERROR,25P02,"current transaction is aborted, commands ignored until end of transaction block",,,,,,"select 1",,,""
"could not receive data from client: Connection reset by peer",,,,,,,,,""
the log files is big anyway. if you can specify some pattern to look at the log, that would really help.