[GitHub] [pulsar] lhotari commented on pull request #14320: [Broker] Increase default numHttpServerThreads value to 200 to prevent Admin API unavailability

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lhotari commented on pull request #14320:
URL: https://github.com/apache/pulsar/pull/14320#issuecomment-1041527088


   > What's the reason of setting the default value to 200? If the node just have one core, what will happen? Please send email to dev mail list to discuss.
   
   These are threads. Jetty defaults to 200 maximum threads, to prevent thread pool starvation. This is recommended when using blocking Servlet API. The problem is that Pulsar uses the blocking servlet API and doesn't have a sufficient amount of threads which are needed and recommended.
   
   The value 200 doesn't mean that there will be 200 threads to start with. This is the maximum size for the thread pool. When the value is more than 8, Jetty will start with 8 initial threads and add more threads to the pool when all threads are occupied.
   
   I have already started an email discussion to discuss this topic. Please reply to https://lists.apache.org/thread/byg1g081o6mfj0xn8ntryvb5qplmrjyl .
   
   There is useful background information in https://lists.apache.org/thread/hso8qwsv40ccrk116fj5ggdpt3b9d4g4 . I wrote that reply before I noticed Penghui's response. It contains a link to Jetty's documenation about asynchronous servlets: https://wiki.eclipse.org/Jetty/Feature/Continuations#Why_Asynchronous_Servlets_.3F .
   
   
   
   


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