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https://issues.apache.org/jira/browse/ZOOKEEPER-2770?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16091065#comment-16091065
]
ASF GitHub Bot commented on ZOOKEEPER-2770:
-------------------------------------------
Github user tdunning commented on a diff in the pull request:
https://github.com/apache/zookeeper/pull/307#discussion_r127877506
--- 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 --
There is a sync() call that ZK supports on the client side. It waits until
the replica that the client is connected to catches up with the leader.
This solves lots of timing issues and is typically the way to implement
read-what-you-wrote.
On the other hand, if your test is running with server internals, this
isn't likely to work as such.
The point is that if you wait until all pending items in the queue have
been committed to all followers, you will be guaranteed to see all writes you
caused before starting to wait.
> ZooKeeper slow operation log
> ----------------------------
>
> Key: ZOOKEEPER-2770
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2770
> Project: ZooKeeper
> Issue Type: Improvement
> Reporter: Karan Mehta
> Assignee: Karan Mehta
> Attachments: ZOOKEEPER-2770.001.patch, ZOOKEEPER-2770.002.patch,
> ZOOKEEPER-2770.003.patch
>
>
> ZooKeeper is a complex distributed application. There are many reasons why
> any given read or write operation may become slow: a software bug, a protocol
> problem, a hardware issue with the commit log(s), a network issue. If the
> problem is constant it is trivial to come to an understanding of the cause.
> However in order to diagnose intermittent problems we often don't know where,
> or when, to begin looking. We need some sort of timestamped indication of the
> problem. Although ZooKeeper is not a datastore, it does persist data, and can
> suffer intermittent performance degradation, and should consider implementing
> a 'slow query' log, a feature very common to services which persist
> information on behalf of clients which may be sensitive to latency while
> waiting for confirmation of successful persistence.
> Log the client and request details if the server discovers, when finally
> processing the request, that the current time minus arrival time of the
> request is beyond a configured threshold.
> Look at the HBase {{responseTooSlow}} feature for inspiration.
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