Passenger 6.0.27 – spawn failure with errno=24, very high number of open FDs #2637
Description
We’re running Passenger on a shared hosting environment, where users run their own applications via Passenger. On Passenger 6.0.27 we’re seeing cases where an application fails to start.
From passenger.log:
[ E 2025-12-14 12:58:08.0616 58412/Tjw3 age/Cor/App/Implementation.cpp:218 ]:
Could not spawn process for application <REDACTED_APP_PATH>:
An operating system error occurred while preparing to spawn an application process:
Error looking up OS group account 1000: Too many open files (errno=24)
At the same time, PassengerAgent ends up with a very large number of open file descriptors (around 80k+).
System limits are high (openfiles 3771288), so it doesn’t look like a ulimit problem.
On Passenger 6.0.22 this setup was working fine: PassengerAgent typically had around 200 open files, not tens of thousands.
After attaching truss to PassengerAgent, the process crashed, and after restart the problem temporarily disappeared.