ab test failed

[AlPasser]

Hi, I tried to replace gzip with zstd. So I did an ab test.
This is for gzip
ab -s 120 -c 1000 -n 200000 -H "Accept-Encoding: gzip" -T "application/json" -p test1.json ip:port/health_check/check
I got my ab reports finnally.
And then I tried this:
ab -s 120 -c 1000 -n 200000 -H "Accept-Encoding: zstd" -T "application/json" -p test1.json ip:port/health_check/check
ab exited with this:
apr_socket_recv: Connection reset by peer (104)
Total of 2317 requests completed
I checked the nginx error.log, found some wokers exited like this:
2023/03/01 20:10:26 [alert] 12898#0: worker process 12917 exited on signal 9
Any advices will be helpful, thx!

[tokers]

Signal 9 means the worker process was killed with SIGKILL. Could you checkout the dmesg output? Maybe this process was killed by the OOM killer.

[AlPasser]

I found out that zstd_comp_level was set too large:
zstd_comp_level 16;
After some tests, I got the result:

1. The compression speed of zstd_comp_level 2 is almost equal to gzip_comp_level 6
2. As for zstd_comp_level 2 and gzip_comp_level 6, when HTML docs is larger than 2KB, $zstd_ratio beats $gzip_ratio