Friday, November 11, 2022

[389-users] FileDescriptors exhausted


we're observing the following error message:
"ERR - accept_and_configure - PR_Accept() failed, Netscape Portable Runtime error -5971 (Process open FD table is full.)"
Looks like the file descriptors are exhausted, probably mainly used by incoming TCP Connections (based on our investigation regarding open FDs).
We've set (and checked using the runtime information in /proc/PID/limits) the ulimits and the nsslapd-maxdescriptors to many thousands (while having about 1000 open connection regularly)

We are investigating in multiple directions here, and have some questions - any input is appreciated:

1) We acknowledge that exhausted FDs prevent additional connections to be opened. But we also see, that existing connections are getting unusable, too. Is this a known behaviour? Can this be avoided?
2) Is there any chance to limit the number of open connections (lower than the max FDs)? (trying to achieve that existing connections still work)
3) What are best practice to prevent the ldap server from getting completely useless (until restart) if a client opens many connections?
4) Any additional remarks to prevent this situation?

Kind regards

Tobias Ernstberger
IBM Security

IBM Deutschland GmbH
Vorsitzender des Aufsichtsrats: Sebastian Krause
Geschäftsführung: Gregor Pillen (Vorsitzender), Nicole Reimer, Gabriele Schwarenthorer, Christine Rupp, Frank Theisen
Sitz der Gesellschaft: Ehningen / Registergericht: Amtsgericht Stuttgart, HRB 14562 / WEEE-Reg.-Nr. DE 99369940
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