tests: event_loop: increase eplison on linux.

[pwhelan]

Summary

The event loop has multiple time epsilons defined, one for each operating system, which defines the longest time delta that is acceptable for a wait or timeout when running timers in the event loop. This delta can easily be exceeded when either running on over-provisioned machines, running other tasks on the same hardware, etc...

This pull request increases this epsilon from 20ms to 50ms for linux. I arrived at this number by running the tests in 1024 parallel instances using GNU parallel while running sysbench on the same AMD Ryzen 9 5900X 12-Core Processor.

The script I used to run the parallel instances of the test:

#!/bin/bash

NUM=1024
parallel --joblog job.log -j 1024 ./test.sh {1} ::: {1..1024}
if cat job.log | awk -F ' ' '{print $7}' | grep -v "0\|Exitval"; then
	exit 1
fi

#!/bin/bash

./bin/flb-it-flb_event_loop test_non_blocking_and_blocking_timeout

I used two scripts simply to mask the fact that GNU parallel needs to pass different arguments to each instance.

I ran tests.sh in a while loop while running sysbench in another terminal:

sysbench cpu run --cpu-max-prime=100000000 --threads=24

I was able to successfully run the test script multiple times for the entire duration of the sysbench test without any failures. My machine might be overpowered compared to the actual runners at github which might justify raising the epsilon even more.

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Testing
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• Example configuration file for the change
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• Backport to latest stable release.

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Fluent Bit is licensed under Apache 2.0, by submitting this pull request I understand that this code will be released under the terms of that license.

[edsiper]

@pwhelan thanks for submitting this PR. some comments:

there is a commit subject called fleet, that one needs to be adjusted.

The whole PR description is about fixing the test framework but there are commits for in_calyptia_fleet plugin , please submit those in a different PR

[pwhelan]

@pwhelan thanks for submitting this PR. some comments:

there is a commit subject called fleet, that one needs to be adjusted.

The whole PR description is about fixing the test framework but there are commits for in_calyptia_fleet plugin , please submit those in a different PR

Sorry, that must have slipped in. I'll rebase the change on top of master, correctly.

@edsiper I accidentally initially based the branch off of #8102 since it was meant as a fixed to a test that it is failing.

[pwhelan]

There is another failure on macOS for flb-rt-dummy I plan to tackle in another PR: https://github.com/fluent/fluent-bit/actions/runs/7092496098/job/19414115930?pr=8246#step:4:4669

[2023/12/07 14:35:32] [ info] [input] pausing dummy.0
[ FAILED ]
  in_dummy.c:538: Check records->num_records >= 20... failed
FAILED: 1 of 1 unit tests has failed.

[edsiper]

note: prefix must be tests: internal: event_loop: ...