[jira] [Resolved] (HIVE-26677) Constrain available processors to Jetty during test runs to prevent thread exhaustion.

["Ádám Szita (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HIVE-26677?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Ádám Szita resolved HIVE-26677.
-------------------------------
    Fix Version/s: 4.0.0
       Resolution: Fixed

+1, merged to master. Thanks for the contribution Chris.

> Constrain available processors to Jetty during test runs to prevent thread exhaustion.
> --------------------------------------------------------------------------------------
>
>                 Key: HIVE-26677
>                 URL: https://issues.apache.org/jira/browse/HIVE-26677
>             Project: Hive
>          Issue Type: Test
>          Components: Test
>            Reporter: Chris Nauroth
>            Assignee: Chris Nauroth
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 4.0.0
>
>          Time Spent: 0.5h
>  Remaining Estimate: 0h
>
> As described during a [release candidate vote|https://lists.apache.org/thread/8qjf7x9t9v09d79hlzh712ls4zthdwrh]:
> HIVE-24484 introduced a change to limit {{hive.server2.webui.max.threads}} to 4. Jetty enforces thread leasing to warn or abort if there aren't enough threads available [1]. During startup, it attempts to lease a thread per NIO selector [2]. By default, the number of NIO selectors to use is determined based on available CPUs [3]. This is mostly a passthrough to {{Runtime.availableProcessors()}} [4]. In my case, running on a machine with 16 CPUs, this ended up creating more than 4 selectors, therefore requiring more than 4 threads and violating the lease check. I was able to work around this by passing the {{JETTY_AVAILABLE_PROCESSORS}} system property to constrain the number of CPUs available to Jetty.
> Since we are intentionally constraining the pool to 4 threads during itests, let's also limit {{JETTY_AVAILABLE_PROCESSORS}} in {{maven.test.jvm.args}} of the root pom.xml, so that others don't run into this problem later.
> [1] https://github.com/eclipse/jetty.project/blob/jetty-9.4.40.v20210413/jetty-util/src/main/java/org/eclipse/jetty/util/thread/ThreadPoolBudget.java#L165
> [2] https://github.com/eclipse/jetty.project/blob/jetty-9.4.40.v20210413/jetty-io/src/main/java/org/eclipse/jetty/io/SelectorManager.java#L255
> [3] https://github.com/eclipse/jetty.project/blob/jetty-9.4.40.v20210413/jetty-io/src/main/java/org/eclipse/jetty/io/SelectorManager.java#L79
> [4] https://github.com/eclipse/jetty.project/blob/jetty-9.4.40.v20210413/jetty-util/src/main/java/org/eclipse/jetty/util/ProcessorUtils.java#L45



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