[jira] [Commented] (HBASE-5572) KeeperException.SessionExpiredException management could be improved in Master
[
https://issues.apache.org/jira/browse/HBASE-5572?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13231693#comment-13231693
]
Hudson commented on HBASE-5572:
---
Integrated in HBase-TRUNK #2686 (See
[https://builds.apache.org/job/HBase-TRUNK/2686/])
HBASE-5549 HBASE-5572 Master can fail if ZooKeeper session expires (N
Keywal) (Revision 1301775)
Result = SUCCESS
tedyu :
Files :
*
/hbase/trunk/src/main/java/org/apache/hadoop/hbase/master/ActiveMasterManager.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/master/HMaster.java
*
/hbase/trunk/src/main/java/org/apache/hadoop/hbase/zookeeper/RecoverableZooKeeper.java
*
/hbase/trunk/src/main/java/org/apache/hadoop/hbase/zookeeper/ZooKeeperWatcher.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/HBaseTestingUtility.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/TestZooKeeper.java
*
/hbase/trunk/src/test/java/org/apache/hadoop/hbase/master/TestDistributedLogSplitting.java
*
/hbase/trunk/src/test/java/org/apache/hadoop/hbase/master/TestMasterZKSessionRecovery.java
*
/hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/TestSplitTransactionOnCluster.java
*
/hbase/trunk/src/test/java/org/apache/hadoop/hbase/replication/TestReplication.java
*
/hbase/trunk/src/test/java/org/apache/hadoop/hbase/replication/TestReplicationPeer.java
KeeperException.SessionExpiredException management could be improved in Master
--
Key: HBASE-5572
URL: https://issues.apache.org/jira/browse/HBASE-5572
Project: HBase
Issue Type: Improvement
Components: master
Affects Versions: 0.96.0
Reporter: nkeywal
Assignee: nkeywal
Priority: Minor
Fix For: 0.96.0
Attachments: 5572.v1.patch, 5572.v2.patch, 5572.v2.patch,
5572.v2.patch
Synthesis:
1) TestMasterZKSessionRecovery distinguish two cases on
SessionExpiredException. One is explicitly not managed. However, is seems
that there is no reason for this.
2) The issue lies in ActiveMasterManager#blockUntilBecomingActiveMaster, a
quite complex function, with a useless recursive call.
3) TestMasterZKSessionRecovery#testMasterZKSessionRecoverySuccess is
equivalent to TestZooKeeper#testMasterSessionExpired
4) TestMasterZKSessionRecovery#testMasterZKSessionRecoveryFailure can be
removed if we merge the two cases mentioned above.
Changes are:
2) Changing ActiveMasterManager#blockUntilBecomingActiveMaster to have a
single case and remove recursion
1) Removing TestMasterZKSessionRecovery
Detailed justification:
testMasterZKSessionRecoveryFailure says:
{noformat}
/**
* Negative test of master recovery from zk session expiry.
*
* Starts with one master. Fakes the master zk session expired.
* Ensures the master cannot recover the expired zk session since
* the master zk node is still there.
*/
public void testMasterZKSessionRecoveryFailure() throws Exception {
MiniHBaseCluster cluster = TEST_UTIL.getHBaseCluster();
HMaster m = cluster.getMaster();
m.abort(Test recovery from zk session expired,
new KeeperException.SessionExpiredException());
assertTrue(m.isStopped());
}
{noformat}
This tests works, i.e. the assertion is always verified.
But do we really want this behavior?
When looking at the code, we see that this what's happening is strange:
- HMaster#abort calls Master#abortNow. If HMaster#abortNow returns false
HMaster#abort stops the master.
- HMaster#abortNow checks the exception type. As it's a
SessionExpiredException it will try to recover, calling
HMaster#tryRecoveringExpiredZKSession. If it cannot, it will return false
(and that will make HMaster#abort stopping the master)
- HMaster#tryRecoveringExpiredZKSession recreates a ZooKeeperConnection and
then try to become the active master. If it cannot, it will return false (and
that will make HMaster#abort stopping the master).
- HMaster#becomeActiveMaster returns the result of
ActiveMasterManager#blockUntilBecomingActiveMaster.
blockUntilBecomingActiveMaster says it will return false if there is any
error preventing it to become the active master.
- ActiveMasterManager#blockUntilBecomingActiveMaster reads ZK for the master
address. If it's the same port host, it deletes the nodes, that will start
a recursive call to blockUntilBecomingActiveMaster. This second call succeeds
(we became the active master) and return true. This result is ignored by the
first blockUntilBecomingActiveMaster: it return false (even if we actually
became the active master), hence the whole suite call returns false and
HMaster#abort stops the master.
In other words, the comment says Ensures the master cannot recover the
expired zk session since
[jira] [Commented] (HBASE-5572) KeeperException.SessionExpiredException management could be improved in Master
[
https://issues.apache.org/jira/browse/HBASE-5572?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13231854#comment-13231854
]
Hudson commented on HBASE-5572:
---
Integrated in HBase-TRUNK-security #140 (See
[https://builds.apache.org/job/HBase-TRUNK-security/140/])
HBASE-5549 HBASE-5572 Master can fail if ZooKeeper session expires (N
Keywal) (Revision 1301775)
Result = SUCCESS
tedyu :
Files :
*
/hbase/trunk/src/main/java/org/apache/hadoop/hbase/master/ActiveMasterManager.java
* /hbase/trunk/src/main/java/org/apache/hadoop/hbase/master/HMaster.java
*
/hbase/trunk/src/main/java/org/apache/hadoop/hbase/zookeeper/RecoverableZooKeeper.java
*
/hbase/trunk/src/main/java/org/apache/hadoop/hbase/zookeeper/ZooKeeperWatcher.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/HBaseTestingUtility.java
* /hbase/trunk/src/test/java/org/apache/hadoop/hbase/TestZooKeeper.java
*
/hbase/trunk/src/test/java/org/apache/hadoop/hbase/master/TestDistributedLogSplitting.java
*
/hbase/trunk/src/test/java/org/apache/hadoop/hbase/master/TestMasterZKSessionRecovery.java
*
/hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/TestSplitTransactionOnCluster.java
*
/hbase/trunk/src/test/java/org/apache/hadoop/hbase/replication/TestReplication.java
*
/hbase/trunk/src/test/java/org/apache/hadoop/hbase/replication/TestReplicationPeer.java
KeeperException.SessionExpiredException management could be improved in Master
--
Key: HBASE-5572
URL: https://issues.apache.org/jira/browse/HBASE-5572
Project: HBase
Issue Type: Improvement
Components: master
Affects Versions: 0.96.0
Reporter: nkeywal
Assignee: nkeywal
Priority: Minor
Fix For: 0.96.0
Attachments: 5572.v1.patch, 5572.v2.patch, 5572.v2.patch,
5572.v2.patch
Synthesis:
1) TestMasterZKSessionRecovery distinguish two cases on
SessionExpiredException. One is explicitly not managed. However, is seems
that there is no reason for this.
2) The issue lies in ActiveMasterManager#blockUntilBecomingActiveMaster, a
quite complex function, with a useless recursive call.
3) TestMasterZKSessionRecovery#testMasterZKSessionRecoverySuccess is
equivalent to TestZooKeeper#testMasterSessionExpired
4) TestMasterZKSessionRecovery#testMasterZKSessionRecoveryFailure can be
removed if we merge the two cases mentioned above.
Changes are:
2) Changing ActiveMasterManager#blockUntilBecomingActiveMaster to have a
single case and remove recursion
1) Removing TestMasterZKSessionRecovery
Detailed justification:
testMasterZKSessionRecoveryFailure says:
{noformat}
/**
* Negative test of master recovery from zk session expiry.
*
* Starts with one master. Fakes the master zk session expired.
* Ensures the master cannot recover the expired zk session since
* the master zk node is still there.
*/
public void testMasterZKSessionRecoveryFailure() throws Exception {
MiniHBaseCluster cluster = TEST_UTIL.getHBaseCluster();
HMaster m = cluster.getMaster();
m.abort(Test recovery from zk session expired,
new KeeperException.SessionExpiredException());
assertTrue(m.isStopped());
}
{noformat}
This tests works, i.e. the assertion is always verified.
But do we really want this behavior?
When looking at the code, we see that this what's happening is strange:
- HMaster#abort calls Master#abortNow. If HMaster#abortNow returns false
HMaster#abort stops the master.
- HMaster#abortNow checks the exception type. As it's a
SessionExpiredException it will try to recover, calling
HMaster#tryRecoveringExpiredZKSession. If it cannot, it will return false
(and that will make HMaster#abort stopping the master)
- HMaster#tryRecoveringExpiredZKSession recreates a ZooKeeperConnection and
then try to become the active master. If it cannot, it will return false (and
that will make HMaster#abort stopping the master).
- HMaster#becomeActiveMaster returns the result of
ActiveMasterManager#blockUntilBecomingActiveMaster.
blockUntilBecomingActiveMaster says it will return false if there is any
error preventing it to become the active master.
- ActiveMasterManager#blockUntilBecomingActiveMaster reads ZK for the master
address. If it's the same port host, it deletes the nodes, that will start
a recursive call to blockUntilBecomingActiveMaster. This second call succeeds
(we became the active master) and return true. This result is ignored by the
first blockUntilBecomingActiveMaster: it return false (even if we actually
became the active master), hence the whole suite call returns false and
HMaster#abort stops the master.
In other words, the comment says Ensures the master cannot recover the
expired zk
[jira] [Commented] (HBASE-5572) KeeperException.SessionExpiredException management could be improved in Master
[
https://issues.apache.org/jira/browse/HBASE-5572?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13230035#comment-13230035
]
nkeywal commented on HBASE-5572:
@stack: it seems the patch could be committed?
KeeperException.SessionExpiredException management could be improved in Master
--
Key: HBASE-5572
URL: https://issues.apache.org/jira/browse/HBASE-5572
Project: HBase
Issue Type: Improvement
Components: master
Affects Versions: 0.96.0
Reporter: nkeywal
Assignee: nkeywal
Priority: Minor
Fix For: 0.96.0
Attachments: 5572.v1.patch, 5572.v2.patch, 5572.v2.patch,
5572.v2.patch
Synthesis:
1) TestMasterZKSessionRecovery distinguish two cases on
SessionExpiredException. One is explicitly not managed. However, is seems
that there is no reason for this.
2) The issue lies in ActiveMasterManager#blockUntilBecomingActiveMaster, a
quite complex function, with a useless recursive call.
3) TestMasterZKSessionRecovery#testMasterZKSessionRecoverySuccess is
equivalent to TestZooKeeper#testMasterSessionExpired
4) TestMasterZKSessionRecovery#testMasterZKSessionRecoveryFailure can be
removed if we merge the two cases mentioned above.
Changes are:
2) Changing ActiveMasterManager#blockUntilBecomingActiveMaster to have a
single case and remove recursion
1) Removing TestMasterZKSessionRecovery
Detailed justification:
testMasterZKSessionRecoveryFailure says:
{noformat}
/**
* Negative test of master recovery from zk session expiry.
*
* Starts with one master. Fakes the master zk session expired.
* Ensures the master cannot recover the expired zk session since
* the master zk node is still there.
*/
public void testMasterZKSessionRecoveryFailure() throws Exception {
MiniHBaseCluster cluster = TEST_UTIL.getHBaseCluster();
HMaster m = cluster.getMaster();
m.abort(Test recovery from zk session expired,
new KeeperException.SessionExpiredException());
assertTrue(m.isStopped());
}
{noformat}
This tests works, i.e. the assertion is always verified.
But do we really want this behavior?
When looking at the code, we see that this what's happening is strange:
- HMaster#abort calls Master#abortNow. If HMaster#abortNow returns false
HMaster#abort stops the master.
- HMaster#abortNow checks the exception type. As it's a
SessionExpiredException it will try to recover, calling
HMaster#tryRecoveringExpiredZKSession. If it cannot, it will return false
(and that will make HMaster#abort stopping the master)
- HMaster#tryRecoveringExpiredZKSession recreates a ZooKeeperConnection and
then try to become the active master. If it cannot, it will return false (and
that will make HMaster#abort stopping the master).
- HMaster#becomeActiveMaster returns the result of
ActiveMasterManager#blockUntilBecomingActiveMaster.
blockUntilBecomingActiveMaster says it will return false if there is any
error preventing it to become the active master.
- ActiveMasterManager#blockUntilBecomingActiveMaster reads ZK for the master
address. If it's the same port host, it deletes the nodes, that will start
a recursive call to blockUntilBecomingActiveMaster. This second call succeeds
(we became the active master) and return true. This result is ignored by the
first blockUntilBecomingActiveMaster: it return false (even if we actually
became the active master), hence the whole suite call returns false and
HMaster#abort stops the master.
In other words, the comment says Ensures the master cannot recover the
expired zk session since the master zk node is still there. but we're
actually doing a check just for this and deleting the node. If we were not
ignoring the result, we would return true, so we would not stop the master,
so the test would fail.
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[jira] [Commented] (HBASE-5572) KeeperException.SessionExpiredException management could be improved in Master
[
https://issues.apache.org/jira/browse/HBASE-5572?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13228460#comment-13228460
]
stack commented on HBASE-5572:
--
@N Thanks for digging in. So, it looks like your patch retains the behavior
where if the current master has same host and port, we'll expire it, and then
try and register ourselves (because we go around to the top of your new while
loop)? Is that so? I believe we have a test to ensure this behavior IIRC.
Patch looks good. +1.
KeeperException.SessionExpiredException management could be improved in Master
--
Key: HBASE-5572
URL: https://issues.apache.org/jira/browse/HBASE-5572
Project: HBase
Issue Type: Improvement
Components: master
Affects Versions: 0.96.0
Reporter: nkeywal
Assignee: nkeywal
Priority: Minor
Attachments: 5572.v1.patch
Synthesis:
1) TestMasterZKSessionRecovery distinguish two cases on
SessionExpiredException. One is explicitly not managed. However, is seems
that there is no reason for this.
2) The issue lies in ActiveMasterManager#blockUntilBecomingActiveMaster, a
quite complex function, with a useless recursive call.
3) TestMasterZKSessionRecovery#testMasterZKSessionRecoverySuccess is
equivalent to TestZooKeeper#testMasterSessionExpired
4) TestMasterZKSessionRecovery#testMasterZKSessionRecoveryFailure can be
removed if we merge the two cases mentioned above.
Changes are:
2) Changing ActiveMasterManager#blockUntilBecomingActiveMaster to have a
single case and remove recursion
1) Removing TestMasterZKSessionRecovery
Detailed justification:
testMasterZKSessionRecoveryFailure says:
{noformat}
/**
* Negative test of master recovery from zk session expiry.
*
* Starts with one master. Fakes the master zk session expired.
* Ensures the master cannot recover the expired zk session since
* the master zk node is still there.
*/
public void testMasterZKSessionRecoveryFailure() throws Exception {
MiniHBaseCluster cluster = TEST_UTIL.getHBaseCluster();
HMaster m = cluster.getMaster();
m.abort(Test recovery from zk session expired,
new KeeperException.SessionExpiredException());
assertTrue(m.isStopped());
}
{noformat}
This tests works, i.e. the assertion is always verified.
But do we really want this behavior?
When looking at the code, we see that this what's happening is strange:
- HMaster#abort calls Master#abortNow. If HMaster#abortNow returns false
HMaster#abort stops the master.
- HMaster#abortNow checks the exception type. As it's a
SessionExpiredException it will try to recover, calling
HMaster#tryRecoveringExpiredZKSession. If it cannot, it will return false
(and that will make HMaster#abort stopping the master)
- HMaster#tryRecoveringExpiredZKSession recreates a ZooKeeperConnection and
then try to become the active master. If it cannot, it will return false (and
that will make HMaster#abort stopping the master).
- HMaster#becomeActiveMaster returns the result of
ActiveMasterManager#blockUntilBecomingActiveMaster.
blockUntilBecomingActiveMaster says it will return false if there is any
error preventing it to become the active master.
- ActiveMasterManager#blockUntilBecomingActiveMaster reads ZK for the master
address. If it's the same port host, it deletes the nodes, that will start
a recursive call to blockUntilBecomingActiveMaster. This second call succeeds
(we became the active master) and return true. This result is ignored by the
first blockUntilBecomingActiveMaster: it return false (even if we actually
became the active master), hence the whole suite call returns false and
HMaster#abort stops the master.
In other words, the comment says Ensures the master cannot recover the
expired zk session since the master zk node is still there. but we're
actually doing a check just for this and deleting the node. If we were not
ignoring the result, we would return true, so we would not stop the master,
so the test would fail.
--
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[jira] [Commented] (HBASE-5572) KeeperException.SessionExpiredException management could be improved in Master
[
https://issues.apache.org/jira/browse/HBASE-5572?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13228476#comment-13228476
]
nkeywal commented on HBASE-5572:
Yes. I've done 3 modifications in the code, two like for like (hopefully!) and
one with a different behavior. I:
- removed the variable named cleanSetOfActiveMaster, replaced by return true
or return false.
- replaced the recursive call by a while(true) loop.
- implicitly (it's hidden because there is no recursive call anymore) changed
the function behavior: we now return the final result. For this reason the
function behaves differently (we return true instead of false), but it's more
on line with the method contract. This change breaks the
testMasterZKSessionRecoveryFailure, because it does not fail anymore.
TestMasterZKSessionRecovery#testMasterZKSessionRecoveryFailure was testing
explicitly the behavior with both SessionExpired AND master with same host
port. I removed it, but I can move it to TestZooKeeper (to save a cluster
start/stop) and reverse the assertion in the test (now it does not fail).
KeeperException.SessionExpiredException management could be improved in Master
--
Key: HBASE-5572
URL: https://issues.apache.org/jira/browse/HBASE-5572
Project: HBase
Issue Type: Improvement
Components: master
Affects Versions: 0.96.0
Reporter: nkeywal
Assignee: nkeywal
Priority: Minor
Attachments: 5572.v1.patch
Synthesis:
1) TestMasterZKSessionRecovery distinguish two cases on
SessionExpiredException. One is explicitly not managed. However, is seems
that there is no reason for this.
2) The issue lies in ActiveMasterManager#blockUntilBecomingActiveMaster, a
quite complex function, with a useless recursive call.
3) TestMasterZKSessionRecovery#testMasterZKSessionRecoverySuccess is
equivalent to TestZooKeeper#testMasterSessionExpired
4) TestMasterZKSessionRecovery#testMasterZKSessionRecoveryFailure can be
removed if we merge the two cases mentioned above.
Changes are:
2) Changing ActiveMasterManager#blockUntilBecomingActiveMaster to have a
single case and remove recursion
1) Removing TestMasterZKSessionRecovery
Detailed justification:
testMasterZKSessionRecoveryFailure says:
{noformat}
/**
* Negative test of master recovery from zk session expiry.
*
* Starts with one master. Fakes the master zk session expired.
* Ensures the master cannot recover the expired zk session since
* the master zk node is still there.
*/
public void testMasterZKSessionRecoveryFailure() throws Exception {
MiniHBaseCluster cluster = TEST_UTIL.getHBaseCluster();
HMaster m = cluster.getMaster();
m.abort(Test recovery from zk session expired,
new KeeperException.SessionExpiredException());
assertTrue(m.isStopped());
}
{noformat}
This tests works, i.e. the assertion is always verified.
But do we really want this behavior?
When looking at the code, we see that this what's happening is strange:
- HMaster#abort calls Master#abortNow. If HMaster#abortNow returns false
HMaster#abort stops the master.
- HMaster#abortNow checks the exception type. As it's a
SessionExpiredException it will try to recover, calling
HMaster#tryRecoveringExpiredZKSession. If it cannot, it will return false
(and that will make HMaster#abort stopping the master)
- HMaster#tryRecoveringExpiredZKSession recreates a ZooKeeperConnection and
then try to become the active master. If it cannot, it will return false (and
that will make HMaster#abort stopping the master).
- HMaster#becomeActiveMaster returns the result of
ActiveMasterManager#blockUntilBecomingActiveMaster.
blockUntilBecomingActiveMaster says it will return false if there is any
error preventing it to become the active master.
- ActiveMasterManager#blockUntilBecomingActiveMaster reads ZK for the master
address. If it's the same port host, it deletes the nodes, that will start
a recursive call to blockUntilBecomingActiveMaster. This second call succeeds
(we became the active master) and return true. This result is ignored by the
first blockUntilBecomingActiveMaster: it return false (even if we actually
became the active master), hence the whole suite call returns false and
HMaster#abort stops the master.
In other words, the comment says Ensures the master cannot recover the
expired zk session since the master zk node is still there. but we're
actually doing a check just for this and deleting the node. If we were not
ignoring the result, we would return true, so we would not stop the master,
so the test would fail.
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[jira] [Commented] (HBASE-5572) KeeperException.SessionExpiredException management could be improved in Master
[
https://issues.apache.org/jira/browse/HBASE-5572?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13228487#comment-13228487
]
stack commented on HBASE-5572:
--
Above sounds good. Would suggest we retain the test that verifies that we
expire znode if same host and port. That behavior can be useful in the
single-master case.
KeeperException.SessionExpiredException management could be improved in Master
--
Key: HBASE-5572
URL: https://issues.apache.org/jira/browse/HBASE-5572
Project: HBase
Issue Type: Improvement
Components: master
Affects Versions: 0.96.0
Reporter: nkeywal
Assignee: nkeywal
Priority: Minor
Attachments: 5572.v1.patch
Synthesis:
1) TestMasterZKSessionRecovery distinguish two cases on
SessionExpiredException. One is explicitly not managed. However, is seems
that there is no reason for this.
2) The issue lies in ActiveMasterManager#blockUntilBecomingActiveMaster, a
quite complex function, with a useless recursive call.
3) TestMasterZKSessionRecovery#testMasterZKSessionRecoverySuccess is
equivalent to TestZooKeeper#testMasterSessionExpired
4) TestMasterZKSessionRecovery#testMasterZKSessionRecoveryFailure can be
removed if we merge the two cases mentioned above.
Changes are:
2) Changing ActiveMasterManager#blockUntilBecomingActiveMaster to have a
single case and remove recursion
1) Removing TestMasterZKSessionRecovery
Detailed justification:
testMasterZKSessionRecoveryFailure says:
{noformat}
/**
* Negative test of master recovery from zk session expiry.
*
* Starts with one master. Fakes the master zk session expired.
* Ensures the master cannot recover the expired zk session since
* the master zk node is still there.
*/
public void testMasterZKSessionRecoveryFailure() throws Exception {
MiniHBaseCluster cluster = TEST_UTIL.getHBaseCluster();
HMaster m = cluster.getMaster();
m.abort(Test recovery from zk session expired,
new KeeperException.SessionExpiredException());
assertTrue(m.isStopped());
}
{noformat}
This tests works, i.e. the assertion is always verified.
But do we really want this behavior?
When looking at the code, we see that this what's happening is strange:
- HMaster#abort calls Master#abortNow. If HMaster#abortNow returns false
HMaster#abort stops the master.
- HMaster#abortNow checks the exception type. As it's a
SessionExpiredException it will try to recover, calling
HMaster#tryRecoveringExpiredZKSession. If it cannot, it will return false
(and that will make HMaster#abort stopping the master)
- HMaster#tryRecoveringExpiredZKSession recreates a ZooKeeperConnection and
then try to become the active master. If it cannot, it will return false (and
that will make HMaster#abort stopping the master).
- HMaster#becomeActiveMaster returns the result of
ActiveMasterManager#blockUntilBecomingActiveMaster.
blockUntilBecomingActiveMaster says it will return false if there is any
error preventing it to become the active master.
- ActiveMasterManager#blockUntilBecomingActiveMaster reads ZK for the master
address. If it's the same port host, it deletes the nodes, that will start
a recursive call to blockUntilBecomingActiveMaster. This second call succeeds
(we became the active master) and return true. This result is ignored by the
first blockUntilBecomingActiveMaster: it return false (even if we actually
became the active master), hence the whole suite call returns false and
HMaster#abort stops the master.
In other words, the comment says Ensures the master cannot recover the
expired zk session since the master zk node is still there. but we're
actually doing a check just for this and deleting the node. If we were not
ignoring the result, we would return true, so we would not stop the master,
so the test would fail.
--
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[jira] [Commented] (HBASE-5572) KeeperException.SessionExpiredException management could be improved in Master
[
https://issues.apache.org/jira/browse/HBASE-5572?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13228598#comment-13228598
]
stack commented on HBASE-5572:
--
+1 on patch. Waiting on hadoopqa...
KeeperException.SessionExpiredException management could be improved in Master
--
Key: HBASE-5572
URL: https://issues.apache.org/jira/browse/HBASE-5572
Project: HBase
Issue Type: Improvement
Components: master
Affects Versions: 0.96.0
Reporter: nkeywal
Assignee: nkeywal
Priority: Minor
Fix For: 0.96.0
Attachments: 5572.v1.patch, 5572.v2.patch, 5572.v2.patch
Synthesis:
1) TestMasterZKSessionRecovery distinguish two cases on
SessionExpiredException. One is explicitly not managed. However, is seems
that there is no reason for this.
2) The issue lies in ActiveMasterManager#blockUntilBecomingActiveMaster, a
quite complex function, with a useless recursive call.
3) TestMasterZKSessionRecovery#testMasterZKSessionRecoverySuccess is
equivalent to TestZooKeeper#testMasterSessionExpired
4) TestMasterZKSessionRecovery#testMasterZKSessionRecoveryFailure can be
removed if we merge the two cases mentioned above.
Changes are:
2) Changing ActiveMasterManager#blockUntilBecomingActiveMaster to have a
single case and remove recursion
1) Removing TestMasterZKSessionRecovery
Detailed justification:
testMasterZKSessionRecoveryFailure says:
{noformat}
/**
* Negative test of master recovery from zk session expiry.
*
* Starts with one master. Fakes the master zk session expired.
* Ensures the master cannot recover the expired zk session since
* the master zk node is still there.
*/
public void testMasterZKSessionRecoveryFailure() throws Exception {
MiniHBaseCluster cluster = TEST_UTIL.getHBaseCluster();
HMaster m = cluster.getMaster();
m.abort(Test recovery from zk session expired,
new KeeperException.SessionExpiredException());
assertTrue(m.isStopped());
}
{noformat}
This tests works, i.e. the assertion is always verified.
But do we really want this behavior?
When looking at the code, we see that this what's happening is strange:
- HMaster#abort calls Master#abortNow. If HMaster#abortNow returns false
HMaster#abort stops the master.
- HMaster#abortNow checks the exception type. As it's a
SessionExpiredException it will try to recover, calling
HMaster#tryRecoveringExpiredZKSession. If it cannot, it will return false
(and that will make HMaster#abort stopping the master)
- HMaster#tryRecoveringExpiredZKSession recreates a ZooKeeperConnection and
then try to become the active master. If it cannot, it will return false (and
that will make HMaster#abort stopping the master).
- HMaster#becomeActiveMaster returns the result of
ActiveMasterManager#blockUntilBecomingActiveMaster.
blockUntilBecomingActiveMaster says it will return false if there is any
error preventing it to become the active master.
- ActiveMasterManager#blockUntilBecomingActiveMaster reads ZK for the master
address. If it's the same port host, it deletes the nodes, that will start
a recursive call to blockUntilBecomingActiveMaster. This second call succeeds
(we became the active master) and return true. This result is ignored by the
first blockUntilBecomingActiveMaster: it return false (even if we actually
became the active master), hence the whole suite call returns false and
HMaster#abort stops the master.
In other words, the comment says Ensures the master cannot recover the
expired zk session since the master zk node is still there. but we're
actually doing a check just for this and deleting the node. If we were not
ignoring the result, we would return true, so we would not stop the master,
so the test would fail.
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[jira] [Commented] (HBASE-5572) KeeperException.SessionExpiredException management could be improved in Master
[
https://issues.apache.org/jira/browse/HBASE-5572?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13228689#comment-13228689
]
nkeywal commented on HBASE-5572:
for an unknown reason the first two patches didn't make it to hadoop-qa.
Rewriting once again.
KeeperException.SessionExpiredException management could be improved in Master
--
Key: HBASE-5572
URL: https://issues.apache.org/jira/browse/HBASE-5572
Project: HBase
Issue Type: Improvement
Components: master
Affects Versions: 0.96.0
Reporter: nkeywal
Assignee: nkeywal
Priority: Minor
Fix For: 0.96.0
Attachments: 5572.v1.patch, 5572.v2.patch, 5572.v2.patch,
5572.v2.patch
Synthesis:
1) TestMasterZKSessionRecovery distinguish two cases on
SessionExpiredException. One is explicitly not managed. However, is seems
that there is no reason for this.
2) The issue lies in ActiveMasterManager#blockUntilBecomingActiveMaster, a
quite complex function, with a useless recursive call.
3) TestMasterZKSessionRecovery#testMasterZKSessionRecoverySuccess is
equivalent to TestZooKeeper#testMasterSessionExpired
4) TestMasterZKSessionRecovery#testMasterZKSessionRecoveryFailure can be
removed if we merge the two cases mentioned above.
Changes are:
2) Changing ActiveMasterManager#blockUntilBecomingActiveMaster to have a
single case and remove recursion
1) Removing TestMasterZKSessionRecovery
Detailed justification:
testMasterZKSessionRecoveryFailure says:
{noformat}
/**
* Negative test of master recovery from zk session expiry.
*
* Starts with one master. Fakes the master zk session expired.
* Ensures the master cannot recover the expired zk session since
* the master zk node is still there.
*/
public void testMasterZKSessionRecoveryFailure() throws Exception {
MiniHBaseCluster cluster = TEST_UTIL.getHBaseCluster();
HMaster m = cluster.getMaster();
m.abort(Test recovery from zk session expired,
new KeeperException.SessionExpiredException());
assertTrue(m.isStopped());
}
{noformat}
This tests works, i.e. the assertion is always verified.
But do we really want this behavior?
When looking at the code, we see that this what's happening is strange:
- HMaster#abort calls Master#abortNow. If HMaster#abortNow returns false
HMaster#abort stops the master.
- HMaster#abortNow checks the exception type. As it's a
SessionExpiredException it will try to recover, calling
HMaster#tryRecoveringExpiredZKSession. If it cannot, it will return false
(and that will make HMaster#abort stopping the master)
- HMaster#tryRecoveringExpiredZKSession recreates a ZooKeeperConnection and
then try to become the active master. If it cannot, it will return false (and
that will make HMaster#abort stopping the master).
- HMaster#becomeActiveMaster returns the result of
ActiveMasterManager#blockUntilBecomingActiveMaster.
blockUntilBecomingActiveMaster says it will return false if there is any
error preventing it to become the active master.
- ActiveMasterManager#blockUntilBecomingActiveMaster reads ZK for the master
address. If it's the same port host, it deletes the nodes, that will start
a recursive call to blockUntilBecomingActiveMaster. This second call succeeds
(we became the active master) and return true. This result is ignored by the
first blockUntilBecomingActiveMaster: it return false (even if we actually
became the active master), hence the whole suite call returns false and
HMaster#abort stops the master.
In other words, the comment says Ensures the master cannot recover the
expired zk session since the master zk node is still there. but we're
actually doing a check just for this and deleting the node. If we were not
ignoring the result, we would return true, so we would not stop the master,
so the test would fail.
--
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