[GitHub] [pulsar] lhotari edited a comment on pull request #14088: [Issue 11070][Zookeeper] Fix netcat returning early for probe

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lhotari edited a comment on pull request #14088:
URL: https://github.com/apache/pulsar/pull/14088#issuecomment-1027220070


   > If you pipe the command to nc the input stream is closed instantly which leads to nc terminating in certain conditions even before the server is able to send the reply. This leads to an empty output which then leads to a failed health check. This behavior seems to be different for different version of nc (OpenBSD, Linux). Since the cause of the problem is a race condition the "-q 1" will wait one second before the program terminates and the server is able to send the reply. This behavior is reproducable on certain Kubernetes clusters with small nodes and seems to be fixed with this change.
   > 
   > for run in {1..10}; do echo ruok | nc localhost 2181; done => imokimokimokimokimok for run in {1..10}; do echo ruok | nc -q 1 localhost 2181; done => imokimokimokimokimokimokimokimokimokimok
   
   Thanks for the explanation @frederic-kneier . 
   Btw. I've been struggling with the Zookeeper probes and this has been causing some instability in https://github.com/apache/pulsar-helm-chart . Some attempts to improve the situation: 
   https://github.com/apache/pulsar-helm-chart/pull/220
   https://github.com/apache/pulsar-helm-chart/pull/214
   https://github.com/apache/pulsar-helm-chart/pull/202
   
   I just wonder if the value for `-q` should be more than 1? 


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