Are any C++ logging libraries safe to use within fork'ed/exec'ed processes?

Question

boost logging explicitly says it is not.

easylogging++ looks like it sets up extern'ed static state that might be trouble after a fork.

Requirements: log rolling after a certain size, support of logging levels, thread-safe.

I'd be happy with something that even needed to be reinitialized after forking.

mi_k · Accepted Answer · 2018-01-07 13:06:26Z

2

I was successfully using spdlog in such scenario. Just initialize logger after calling fork.

answered Jan 7, 2018 at 13:06

mi_k

212 bronze badges

1

Welcome aboard. this is a good answer (+1), but it is not very helpful. Normally, we ask you to explain why your recommendation meets the OP's needs. In this case, with the main emphasis being on Forking, I note that the page mentions benchmarking with a number of threads, so this should suit the OP's requirements.
– Mawg
Commented Jan 8, 2018 at 12:22
Actually spdlog is not fork-safe. The library employs localtime_r for formatting under the hood, which is not fork-safe. Even if you initialize a new logger in the child process, there is a global mutex in localtime_r implementation, which can be copied into child process in locked state (and from times to times it occurs). I'm currently using the library and trying to workaround the problem.
– nicolai
Commented May 22, 2020 at 8:39

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