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Update git submodules 

* Update tacker from branch 'master'
  to 51167c8aedc44d9d1725865d509b66f637978179
  - Merge "Fix two-stage process launcher in tacker-server"
  - Fix two-stage process launcher in tacker-server
    
    tacker-server has got two-stage process launcher since a long time ago.
    While it doesn't matter if {api_workers} is set to one or unset, which
    is the case by default on installation via devstack, it should have
    resulted in an odd situation in other cases as follows:
    
    1). surprisingly the number of workers was not {api_workers} but
        {api_workers}*{api_workers}. Notice that the launcher processes are
        also present so the resulting number of tacker-server processes was
        1+{api_workers}*({api_workers}+1).
    
        E.g., when {api_workers}=100, the number of tacker-server processes
        is 10101.
    
    2). GreenPool is per the second stage launcher. That means {api_workers}
        number of workers, each of which is a green thread on a seperate
        process (spawned by ProcessLauncher), share the same pool. It means
        that the second stage launcher does not only fail to provide
        performance scaling, but also more likely to unnecessarily keep some
        workers starved due to a process which starts sleeping before
        yielding.
    
    This patch fixes it so that there is just a one-stage launcher.
    
        [Before this patch]
            master
              ├── worker#0 # second-stage launcher
              │   ├── worker#0-0 (*1)
              │   ├── worker#0-1 (*1)
              │   :
              │   └── worker#0-{api_workers-1} (*1)
              ├── worker#1 # second-stage launcher
              :
              └── worker#{api_workers-1}
                  :
                  └── worker#{api_workers-1}-{api_workers-1} (*1)
    
        [After this patch]
            master
              ├── worker#0 (*1)
              ├── worker#1 (*1)
              :
              └── worker#{api_workers-1} (*1)
    
        (*1) spawns one green thread at the start.
    
    Closes-Bug: #1923528
    Change-Id: I2bf567a0367659c170af0b618374a51d0f13eece
This commit is contained in:
Zuul 2021-05-06 07:05:48 +00:00 committed by Gerrit Code Review
parent c8e80d5b65
commit 77feb1f1f2
1 changed files with 1 additions and 1 deletions
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2
tacker

@ -1 +1 @@
Subproject commit 915afe3d379c44784ce497741ffe30f5f689cd96
Subproject commit 51167c8aedc44d9d1725865d509b66f637978179