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Description of problem:
When using fluentd (0.12.x using ruby 2.0 in RHEL7), the memory usage (as measured by ps h -p $fluentdpid -o rss) grows steadily until it runs out of memory and crashes or is OOMkilled.  This seems mostly exacerbated when using fluentd as a listener (using the secure_forward protocol) of other fluentd collectors.

Version-Release number of selected component (if applicable):
RHEL 7 - ruby 2.0 - fluentd 0.12.x

How reproducible:
Every time

Steps to Reproduce:
1. Deploy OpenShift + logging + mux component
2. Put a load on fluentd e.g. logger -f file_with_many_lines
3. Measure rss of the fluentd mux

Actual results:


Expected results:
I would expect the memory usage to eventually plateau instead of growing constantly.

Additional info:
The mux case is the easiest and fastest way to show the memory growth.

If using OCP 3.7 or later, the fluentd is bundled with jemalloc - set the environment variable USE_JEMALLOC=false to disable jemalloc and use glibc malloc.

Thanks Rich, we will work with you on this issue to see what we can determine about fluentd's particular use case that doesn't lead to stable memory usage over time.

I'm moving this bug to RHEL8, but that shouldn't matter here, this is a tracking bug for the purposes of reviewing the workload issues with malloc.

After evaluating this issue, there are no plans to address it further or fix it in an upcoming release.  Therefore, it is being closed.  If plans change such that this issue will be fixed in an upcoming release, then the bug can be reopened.