Event_log shows following message:
[-154773824] 02/06/07 11:53 Warning: Main thread waiting for syncop.done for 60 seconds [sp_opst_mt (for o.opdb-o.ora_splex queue ref_ora_splex)/20128]
post main thread has sent the commit message to the sql thread but the commit has not been executed, therefore post main thread can not dispatch the next message until it receives confirmation from sql thread that the commit has been done.
RESOLUTION:
Event_log may show 'main thread waiting for syncop done for xxx seconds' repeatedly and eventually post may exit and restart with 'max oexn time exceeded cause unknown'. Post will wait for five times the SP_OPO_MAX_OEXN_TIME setting before it exits and restarts post.
Check ASH report and AWR report for the relevant timeframe to see if there are any blocking sessions in database for post process or if there are sqls that are running slow for post.
Review KB119125 on how to troubleshoot post slow issue.
