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From: karanmehta93 <git@git.apache.org>
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Subject: [GitHub] zookeeper pull request #307: ZOOKEEPER-2770 ZooKeeper slow operation log
Content-Type: text/plain
Message-Id: <20170719052200.EF1B4E360F@git1-us-west.apache.org>
Date: Wed, 19 Jul 2017 05:22:00 +0000 (UTC)
archived-at: Wed, 19 Jul 2017 05:22:03 -0000

Github user karanmehta93 commented on a diff in the pull request:

    https://github.com/apache/zookeeper/pull/307#discussion_r128155180
  
    --- Diff: src/java/test/org/apache/zookeeper/server/ZooKeeperServerMainTest.java ---
    @@ -138,14 +145,56 @@ void delete(File f) throws IOException {
             ServerCnxnFactory getCnxnFactory() {
                 return main.getCnxnFactory();
             }
    +
         }
     
    -    public static  class TestZKSMain extends ZooKeeperServerMain {
    +    public static class TestZKSMain extends ZooKeeperServerMain {
    +
    +        private ServerStats serverStats;
    +
    +        @Override
    +        public ZooKeeperServer getZooKeeperServer(FileTxnSnapLog txnLog, ServerConfig config, ZKDatabase zkDb) {
    +            ZooKeeperServer zooKeeperServer = super.getZooKeeperServer(txnLog, config, zkDb);
    +            serverStats = zooKeeperServer.serverStats();
    +            return zooKeeperServer;
    +        }
    +
    +        @Override
             public void shutdown() {
                 super.shutdown();
             }
         }
     
    +    // Test for ZOOKEEPER-2770 ZooKeeper slow operation log
    +    @Test
    +    public void testRequestWarningThreshold() throws IOException, KeeperException, InterruptedException {
    +        ClientBase.setupTestEnv();
    +
    +        final int CLIENT_PORT = PortAssignment.unique();
    +
    +        MainThread main = new MainThread(CLIENT_PORT, true, null, 0);
    +        main.start();
    +
    +        Assert.assertTrue("waiting for server being up",
    +                ClientBase.waitForServerUp("127.0.0.1:" + CLIENT_PORT,
    +                        CONNECTION_TIMEOUT));
    +        // Get the stats object from the ZooKeeperServer to keep track of high latency requests.
    +        ServerStats stats = main.main.serverStats;
    +
    +        ZooKeeper zk = new ZooKeeper("127.0.0.1:" + CLIENT_PORT,
    +                ClientBase.CONNECTION_TIMEOUT, this);
    +
    +        zk.create("/foo1", "foobar".getBytes(), Ids.OPEN_ACL_UNSAFE,
    +                CreateMode.PERSISTENT);
    +
    +        Assert.assertEquals(new String(zk.getData("/foo1", null, null)), "foobar");
    +        // It takes a while for the counter to get updated sometimes, this is added to reduce flakyness
    +        Thread.sleep(1000);
    --- End diff --
    
    > We can always increase the counter before we send a response back to client in FinalRequestProcessor. This will make test deterministic, Or,
    
    Not this approach. It will boil down to the same thing as `ServerStats` which we don't want in the first place. 
    
    > In test, implement retry polling with a timeout and a smaller sleep interval (e..g 10ms instead of 1000ms). We use this pattern a lot in our test. In general we'd like to make deterministic tests as much as possible (in other words, avoid sleep at all cost.) though sometimes that is hard to do due to various reasons.
    
    I will add the polling mechanism with a smaller sleep interval. I would also love to make the test deterministic, however I don't think this will be possible here because of race condition involved between client side and server side processing thread.


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