Thank you for your prompt response and suggestion, Howard. I did try your suggestion and increased the olcListenerThreads (based on number of CPUs) but that did not help. Got the same connection timeout errors when I tried to go beyond 1650 concurrent requests.
Although, I did see something and wanted to run by you - In the "libraries/libldap_r/tpool.c" code file I see that the max threads was defined to "LDAP_MAXTHR 1024". So does that mean the limit on the number of threads for slapd process is 1024 ?
After coming across this setting we changed the number of threads in our load test tool to 1024 for each node and ran that script 100 times in a loop and we were able to successfully complete 204,800 bind requests across 2 nodes in 40 minutes.
If we want to bump up the max thread number further to say 4096 can we do that by just updating the "LDAP_MAXTHR" accordingly ?
Will it affect something else ? Thank you for your help as always !
The larger value will use more memory and may cause a slight slowdown in looking up thread-local variables. Probably not significant.