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https://issues.apache.org/jira/browse/CURATOR-328?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Cameron McKenzie updated CURATOR-328:
-------------------------------------
Fix Version/s: (was: 3.1.1)
(was: 2.10.1)
3.2.0
2.11.0
> PathChildrenCache fails silently if server is unavailable for sufficient time
> when client starts
> ------------------------------------------------------------------------------------------------
>
> Key: CURATOR-328
> URL: https://issues.apache.org/jira/browse/CURATOR-328
> Project: Apache Curator
> Issue Type: Bug
> Components: Recipes
> Affects Versions: 3.1.0, 2.10.0
> Reporter: Gerd Behrmann
> Assignee: Jordan Zimmerman
> Fix For: 2.11.0, 3.2.0
>
>
> When initializing the PathChildrenCache, if the curator client is not yet
> connected to the ZooKeeper server (e.g. the server is down or the network
> connection is unavailable), then the internal initialization of the cache
> will eventually fail silently and the cache stays empty even after the client
> finally connects to the server and the path is populated with znodes.
> The following unit test demonstrates the problem (the unit test is ugly as
> the problem depends on timing, but it suffices to demonstrate the issue):
> {code:java}
> @Test
> public void pathChildrenCacheTest() throws Exception
> {
> TestingServer server = new TestingServer(false);
> Timing timing = new Timing();
> CuratorFramework client = CuratorFrameworkFactory.newClient(
> server.getConnectString(), timing.session(),
> timing.connection(), new ExponentialBackoffRetry(1000, 3));
> try {
> new Thread() {
> @Override
> public void run()
> {
> try {
> Thread.sleep(60000);
> server.start();
> } catch (Exception e) {
> e.printStackTrace();
> }
> }
> }.start();
> client.start();
> PathChildrenCache cache = new PathChildrenCache(client, "/",
> true);
> cache.start();
> client.blockUntilConnected();
>
> client.create().creatingParentContainersIfNeeded().forPath("/baz", new byte[]
> {1,2,3});
> assertNotNull("/baz does not exist",
> client.checkExists().forPath("/baz"));
> /* Ugly hack for this test to ensure the cache got time to update
> itself. */
> Thread.sleep(1000);
> assertNotNull("cache doesn't see /baz",
> cache.getCurrentData("/baz"));
> } finally {
> client.close();
> server.stop();
> }
> }
> {code}
> Here the server startup is delayed until some point after the curator client
> was started and after the recipe has been created. Eventually the server
> starts and the path is populated with data - some time is given for the cache
> to update itself, yet no data is visible: The second assertion fails.
> If the startup time is reduced to - say - 20 seconds, the test passes.
> If the client is allowed to first connect to the server before creating the
> recipe and then disconnect and reconnect after creating the recipe, then the
> test passes too.
> I tracked down the problem to the state change listener of the recipe: If the
> connection to the server is down for long enough, the refresh call during the
> background initialization will eventually fail (ensurePath throws an
> exception). This isn't a problem as the recipe has a state change listener,
> so it gets notified when the client eventually connects to the server. The
> handleStateChange method however doesn't react to a CONNECTED event - only to
> a RECONNECTED event. Thus if the client has been connected to the server in
> the past, everything works, however if this is the first time it connects,
> the recipe will not react to the event and thus not refresh itself.
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