Configuring PID recycle pool on AIX
Posted on 2010-08-18
We have a number of client sites running a custom application against our database, each with 500+ users. The database has associated with it a number of dedicated daemon processes, one of which is responsible for "cleaning up" any processes that exit unexpectedly, occasionally leaving record locks and shared memory which could compromise database integrity. The client's application typically launches many short-lived processes. As a result it is possible for a process to exit and before the daemon has a chance to detect and clean it up, the OS has re-assigned the PID to another process. Needless to say this can cause all manner of problems to the daemon and at its worst, force the daemon to exit and require a database shutdown.
We cannot reduce the sleep time of the daemon any further. The client has gone to 7-digit PIDs anticipating that this will increase the size of the PID pool available to it and hence reduce the chance of the problem arising, but this does not appear to have an basis since the problem still recurs from time to time.
Is there some way to configure the kernel to either:
1) increase the pool size? (there is a pool of PIDs isn't there?)
2) specify some delay period before the PID is re-used?
3) some other way to prevent the situation arising?
Many thanks in advance!