Chris M. Hostetter created SOLR-17478:
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Summary: ZkTestServer bugs can cause 30sec test pauses
Key: SOLR-17478
URL: https://issues.apache.org/jira/browse/SOLR-17478
Project: Solr
Issue Type: Test
Security Level: Public (Default Security Level. Issues are Public)
Reporter: Chris M. Hostetter
Pop Quiz: which of these two (psuedo-code) ZK based test classes will be
faster...
{code:java}
public class Test_X extends SolrTestCase {
public void test() throws Exception {
ZkTestServer zkServer = new ZkTestServer(createTempDir());
zkServer.run();
zkServer.shutdown();
}
}
public class Test_Y extends SolrTestCaseJ4 {
public void test() throws Exception {
ZkTestServer zkServer = new ZkTestServer(createTempDir());
zkServer.run();
zkServer.shutdown();
}
}
{code}
...if you guessed "Test_X, because SolrTestCase has less overhead then
SolrTestCaseJ4" then you are *wrong by ~30 seconds.*
Actually, that's not _always_ true: if you run both tests in the same JVM then
they will both take the same amount of time:
* If Test_Y runs first, they will both take ~1 second each
* If Test_X runs first, they will both take 30+ seconds *_each_*
The reason for the dependency comes down to:
* The {{"zookeeper.4lw.commands.whitelist"}} sysprop is set/cleared in
SolrTestCaseJ4 (BeforeClass/AfterClass), but _NOT_ in SolrTestCase
* ZkTestServer depends on the ZK helper methods
{{ClientBase.waitForServerUp()}} which depends on the 4LW {{"stat"}} being
whitelisted
** If "stat" is not whitelisted, then {{waitForServerUp()}} timesout after 30
sec and return a failure
** Bonus problem: ZkTestServer never checks of the return value of
{{waitForServerUp()}} !
* Zookeeper only checks for the 4LW whitelist sysprop the first time it's
needed by the {{FourLetterCommands}} class _and then caches it staticly_
** So if the first testclass to run a ZK server doesn't extend SolrTestCaseJ4,
then _every_ test that uses ZkTestServer in that JVM will stall for 30 seconds
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