[jira] [Commented] (ZOOKEEPER-1382) Zookeeper server holds onto dead/expired session ids in the watch data structures
[ https://issues.apache.org/jira/browse/ZOOKEEPER-1382?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13575670#comment-13575670 ] Michael Morello commented on ZOOKEEPER-1382: Since we monitor sessions and watches we note that we encounter this problem from time to time. This is not a big issue but it causes a memory leak. I'll try to see if I can work on it but it does seem hard to reproduce in a unit test. Zookeeper server holds onto dead/expired session ids in the watch data structures - Key: ZOOKEEPER-1382 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1382 Project: ZooKeeper Issue Type: Bug Components: server Affects Versions: 3.3.4 Reporter: Neha Narkhede Assignee: Neha Narkhede Priority: Critical Fix For: 3.4.6 Attachments: ZOOKEEPER-1382_3.3.4.patch I've observed that zookeeper server holds onto expired session ids in the watcher data structures. The result is the wchp command reports session ids that cannot be found through cons/dump and those expired session ids sit there maybe until the server is restarted. Here are snippets from the client and the server logs that lead to this state, for one particular session id 0x134485fd7bcb26f - There are 4 servers in the zookeeper cluster - 223, 224, 225 (leader), 226 and I'm using ZkClient to connect to the cluster From the application log - application.log.2012-01-26-325.gz:2012/01/26 04:56:36.177 INFO [ClientCnxn] [main-SendThread(223.prod:12913)] [application Session establishment complete on server 223.prod/172.17.135.38:12913, sessionid = 0x134485fd7bcb26f, negotiated timeout = 6000 application.log.2012-01-27.gz:2012/01/27 09:52:37.714 INFO [ClientCnxn] [main-SendThread(223.prod:12913)] [application] Client session timed out, have not heard from server in 9827ms for sessionid 0x134485fd7bcb26f, closing socket connection and attempting reconnect application.log.2012-01-27.gz:2012/01/27 09:52:38.191 INFO [ClientCnxn] [main-SendThread(226.prod:12913)] [application] Unable to reconnect to ZooKeeper service, session 0x134485fd7bcb26f has expired, closing socket connection On the leader zk, 225 - zookeeper.log.2012-01-27-leader-225.gz:2012-01-27 09:52:34,010 - INFO [SessionTracker:ZooKeeperServer@314] - Expiring session 0x134485fd7bcb26f, timeout of 6000ms exceeded zookeeper.log.2012-01-27-leader-225.gz:2012-01-27 09:52:34,010 - INFO [ProcessThread:-1:PrepRequestProcessor@391] - Processed session termination for sessionid: 0x134485fd7bcb26f On the server, the client was initially connected to, 223 - zookeeper.log.2012-01-26-223.gz:2012-01-26 04:56:36,173 - INFO [CommitProcessor:1:NIOServerCnxn@1580] - Established session 0x134485fd7bcb26f with negotiated timeout 6000 for client /172.17.136.82:45020 zookeeper.log.2012-01-27-223.gz:2012-01-27 09:52:34,018 - INFO [CommitProcessor:1:NIOServerCnxn@1435] - Closed socket connection for client /172.17.136.82:45020 which had sessionid 0x134485fd7bcb26f Here are the log snippets from 226, which is the server, the client reconnected to, before getting session expired event - 2012-01-27 09:52:38,190 - INFO [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:12913:NIOServerCnxn@770] - Client attempting to renew session 0x134485fd7bcb26f at /172.17.136.82:49367 2012-01-27 09:52:38,191 - INFO [QuorumPeer:/0.0.0.0:12913:NIOServerCnxn@1573] - Invalid session 0x134485fd7bcb26f for client /172.17.136.82:49367, probably expired 2012-01-27 09:52:38,191 - INFO [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:12913:NIOServerCnxn@1435] - Closed socket connection for client /172.17.136.82:49367 which had sessionid 0x134485fd7bcb26f wchp output from 226, taken on 01/30 - nnarkhed-ld:zk-cons-wchp-2012013000 nnarkhed$ grep 0x134485fd7bcb26f *226.*wchp* | wc -l 3 wchp output from 223, taken on 01/30 - nnarkhed-ld:zk-cons-wchp-2012013000 nnarkhed$ grep 0x134485fd7bcb26f *223.*wchp* | wc -l 0 cons output from 223 and 226, taken on 01/30 - nnarkhed-ld:zk-cons-wchp-2012013000 nnarkhed$ grep 0x134485fd7bcb26f *226.*cons* | wc -l 0 nnarkhed-ld:zk-cons-wchp-2012013000 nnarkhed$ grep 0x134485fd7bcb26f *223.*cons* | wc -l 0 So, what seems to have happened is that the client was able to re-register the watches on the new server (226), after it got disconnected from 223, inspite of having an expired session id. In NIOServerCnxn, I saw that after suspecting that a session is expired, a server removes the cnxn and its watches from its internal data structures. But before that it allows more requests to be processed even if the session is expired - // Now that the session is ready we can start receiving packets
[jira] [Updated] (ZOOKEEPER-1382) Zookeeper server holds onto dead/expired session ids in the watch data structures
[ https://issues.apache.org/jira/browse/ZOOKEEPER-1382?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ] Michael Morello updated ZOOKEEPER-1382: --- Attachment: ZOOKEEPER-1382.patch I managed to create a JUnit test case that demonstrate the watches leak, unfortunately i had to promote a few methods to the public scope. As Neha pointed out the unit test shows that if a client send a connection request with an expired session the NIOServerCnxn class still processes upcoming messages like OpCode.setWatches. Actually the fix simply consists to call cnxn.enableRecv() only if the session has been validated by the leader. Zookeeper server holds onto dead/expired session ids in the watch data structures - Key: ZOOKEEPER-1382 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1382 Project: ZooKeeper Issue Type: Bug Components: server Affects Versions: 3.4.5 Reporter: Neha Narkhede Assignee: Neha Narkhede Priority: Critical Fix For: 3.4.6 Attachments: ZOOKEEPER-1382_3.3.4.patch, ZOOKEEPER-1382.patch I've observed that zookeeper server holds onto expired session ids in the watcher data structures. The result is the wchp command reports session ids that cannot be found through cons/dump and those expired session ids sit there maybe until the server is restarted. Here are snippets from the client and the server logs that lead to this state, for one particular session id 0x134485fd7bcb26f - There are 4 servers in the zookeeper cluster - 223, 224, 225 (leader), 226 and I'm using ZkClient to connect to the cluster From the application log - application.log.2012-01-26-325.gz:2012/01/26 04:56:36.177 INFO [ClientCnxn] [main-SendThread(223.prod:12913)] [application Session establishment complete on server 223.prod/172.17.135.38:12913, sessionid = 0x134485fd7bcb26f, negotiated timeout = 6000 application.log.2012-01-27.gz:2012/01/27 09:52:37.714 INFO [ClientCnxn] [main-SendThread(223.prod:12913)] [application] Client session timed out, have not heard from server in 9827ms for sessionid 0x134485fd7bcb26f, closing socket connection and attempting reconnect application.log.2012-01-27.gz:2012/01/27 09:52:38.191 INFO [ClientCnxn] [main-SendThread(226.prod:12913)] [application] Unable to reconnect to ZooKeeper service, session 0x134485fd7bcb26f has expired, closing socket connection On the leader zk, 225 - zookeeper.log.2012-01-27-leader-225.gz:2012-01-27 09:52:34,010 - INFO [SessionTracker:ZooKeeperServer@314] - Expiring session 0x134485fd7bcb26f, timeout of 6000ms exceeded zookeeper.log.2012-01-27-leader-225.gz:2012-01-27 09:52:34,010 - INFO [ProcessThread:-1:PrepRequestProcessor@391] - Processed session termination for sessionid: 0x134485fd7bcb26f On the server, the client was initially connected to, 223 - zookeeper.log.2012-01-26-223.gz:2012-01-26 04:56:36,173 - INFO [CommitProcessor:1:NIOServerCnxn@1580] - Established session 0x134485fd7bcb26f with negotiated timeout 6000 for client /172.17.136.82:45020 zookeeper.log.2012-01-27-223.gz:2012-01-27 09:52:34,018 - INFO [CommitProcessor:1:NIOServerCnxn@1435] - Closed socket connection for client /172.17.136.82:45020 which had sessionid 0x134485fd7bcb26f Here are the log snippets from 226, which is the server, the client reconnected to, before getting session expired event - 2012-01-27 09:52:38,190 - INFO [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:12913:NIOServerCnxn@770] - Client attempting to renew session 0x134485fd7bcb26f at /172.17.136.82:49367 2012-01-27 09:52:38,191 - INFO [QuorumPeer:/0.0.0.0:12913:NIOServerCnxn@1573] - Invalid session 0x134485fd7bcb26f for client /172.17.136.82:49367, probably expired 2012-01-27 09:52:38,191 - INFO [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:12913:NIOServerCnxn@1435] - Closed socket connection for client /172.17.136.82:49367 which had sessionid 0x134485fd7bcb26f wchp output from 226, taken on 01/30 - nnarkhed-ld:zk-cons-wchp-2012013000 nnarkhed$ grep 0x134485fd7bcb26f *226.*wchp* | wc -l 3 wchp output from 223, taken on 01/30 - nnarkhed-ld:zk-cons-wchp-2012013000 nnarkhed$ grep 0x134485fd7bcb26f *223.*wchp* | wc -l 0 cons output from 223 and 226, taken on 01/30 - nnarkhed-ld:zk-cons-wchp-2012013000 nnarkhed$ grep 0x134485fd7bcb26f *226.*cons* | wc -l 0 nnarkhed-ld:zk-cons-wchp-2012013000 nnarkhed$ grep 0x134485fd7bcb26f *223.*cons* | wc -l 0 So, what seems to have happened is that the client was able to re-register the watches on the new server (226), after it got disconnected from 223, inspite of having an expired session id. In NIOServerCnxn, I saw that after suspecting that a session is expired, a server removes the cnxn and its
[jira] [Updated] (ZOOKEEPER-1382) Zookeeper server holds onto dead/expired session ids in the watch data structures
[
https://issues.apache.org/jira/browse/ZOOKEEPER-1382?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Michael Morello updated ZOOKEEPER-1382:
---
Attachment: (was: ZOOKEEPER-1382.patch)
Zookeeper server holds onto dead/expired session ids in the watch data
structures
-
Key: ZOOKEEPER-1382
URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1382
Project: ZooKeeper
Issue Type: Bug
Components: server
Affects Versions: 3.4.5
Reporter: Neha Narkhede
Assignee: Neha Narkhede
Priority: Critical
Fix For: 3.4.6
Attachments: ZOOKEEPER-1382_3.3.4.patch
I've observed that zookeeper server holds onto expired session ids in the
watcher data structures. The result is the wchp command reports session ids
that cannot be found through cons/dump and those expired session ids sit
there maybe until the server is restarted. Here are snippets from the client
and the server logs that lead to this state, for one particular session id
0x134485fd7bcb26f -
There are 4 servers in the zookeeper cluster - 223, 224, 225 (leader), 226
and I'm using ZkClient to connect to the cluster
From the application log -
application.log.2012-01-26-325.gz:2012/01/26 04:56:36.177 INFO [ClientCnxn]
[main-SendThread(223.prod:12913)] [application Session establishment complete
on server 223.prod/172.17.135.38:12913, sessionid = 0x134485fd7bcb26f,
negotiated timeout = 6000
application.log.2012-01-27.gz:2012/01/27 09:52:37.714 INFO [ClientCnxn]
[main-SendThread(223.prod:12913)] [application] Client session timed out,
have not heard from server in 9827ms for sessionid 0x134485fd7bcb26f, closing
socket connection and attempting reconnect
application.log.2012-01-27.gz:2012/01/27 09:52:38.191 INFO [ClientCnxn]
[main-SendThread(226.prod:12913)] [application] Unable to reconnect to
ZooKeeper service, session 0x134485fd7bcb26f has expired, closing socket
connection
On the leader zk, 225 -
zookeeper.log.2012-01-27-leader-225.gz:2012-01-27 09:52:34,010 - INFO
[SessionTracker:ZooKeeperServer@314] - Expiring session 0x134485fd7bcb26f,
timeout of 6000ms exceeded
zookeeper.log.2012-01-27-leader-225.gz:2012-01-27 09:52:34,010 - INFO
[ProcessThread:-1:PrepRequestProcessor@391] - Processed session termination
for sessionid: 0x134485fd7bcb26f
On the server, the client was initially connected to, 223 -
zookeeper.log.2012-01-26-223.gz:2012-01-26 04:56:36,173 - INFO
[CommitProcessor:1:NIOServerCnxn@1580] - Established session
0x134485fd7bcb26f with negotiated timeout 6000 for client /172.17.136.82:45020
zookeeper.log.2012-01-27-223.gz:2012-01-27 09:52:34,018 - INFO
[CommitProcessor:1:NIOServerCnxn@1435] - Closed socket connection for client
/172.17.136.82:45020 which had sessionid 0x134485fd7bcb26f
Here are the log snippets from 226, which is the server, the client
reconnected to, before getting session expired event -
2012-01-27 09:52:38,190 - INFO
[NIOServerCxn.Factory:0.0.0.0/0.0.0.0:12913:NIOServerCnxn@770] - Client
attempting to renew session 0x134485fd7bcb26f at /172.17.136.82:49367
2012-01-27 09:52:38,191 - INFO
[QuorumPeer:/0.0.0.0:12913:NIOServerCnxn@1573] - Invalid session
0x134485fd7bcb26f for client /172.17.136.82:49367, probably expired
2012-01-27 09:52:38,191 - INFO
[NIOServerCxn.Factory:0.0.0.0/0.0.0.0:12913:NIOServerCnxn@1435] - Closed
socket connection for client /172.17.136.82:49367 which had sessionid
0x134485fd7bcb26f
wchp output from 226, taken on 01/30 -
nnarkhed-ld:zk-cons-wchp-2012013000 nnarkhed$ grep 0x134485fd7bcb26f
*226.*wchp* | wc -l
3
wchp output from 223, taken on 01/30 -
nnarkhed-ld:zk-cons-wchp-2012013000 nnarkhed$ grep 0x134485fd7bcb26f
*223.*wchp* | wc -l
0
cons output from 223 and 226, taken on 01/30 -
nnarkhed-ld:zk-cons-wchp-2012013000 nnarkhed$ grep 0x134485fd7bcb26f
*226.*cons* | wc -l
0
nnarkhed-ld:zk-cons-wchp-2012013000 nnarkhed$ grep 0x134485fd7bcb26f
*223.*cons* | wc -l
0
So, what seems to have happened is that the client was able to re-register
the watches on the new server (226), after it got disconnected from 223,
inspite of having an expired session id.
In NIOServerCnxn, I saw that after suspecting that a session is expired, a
server removes the cnxn and its watches from its internal data structures.
But before that it allows more requests to be processed even if the session
is expired -
// Now that the session is ready we can start receiving packets
synchronized (this.factory) {
sk.selector().wakeup();
enableRecv();
}
} catch (Exception e) {
LOG.warn(Exception while establishing session, closing, e);
close();
[jira] [Updated] (ZOOKEEPER-1382) Zookeeper server holds onto dead/expired session ids in the watch data structures
[
https://issues.apache.org/jira/browse/ZOOKEEPER-1382?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Michael Morello updated ZOOKEEPER-1382:
---
Attachment: ZOOKEEPER-1382-branch-3.4.patch
Current patch is for branch 3.4
Sorry
Zookeeper server holds onto dead/expired session ids in the watch data
structures
-
Key: ZOOKEEPER-1382
URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1382
Project: ZooKeeper
Issue Type: Bug
Components: server
Affects Versions: 3.4.5
Reporter: Neha Narkhede
Assignee: Neha Narkhede
Priority: Critical
Fix For: 3.4.6
Attachments: ZOOKEEPER-1382_3.3.4.patch,
ZOOKEEPER-1382-branch-3.4.patch
I've observed that zookeeper server holds onto expired session ids in the
watcher data structures. The result is the wchp command reports session ids
that cannot be found through cons/dump and those expired session ids sit
there maybe until the server is restarted. Here are snippets from the client
and the server logs that lead to this state, for one particular session id
0x134485fd7bcb26f -
There are 4 servers in the zookeeper cluster - 223, 224, 225 (leader), 226
and I'm using ZkClient to connect to the cluster
From the application log -
application.log.2012-01-26-325.gz:2012/01/26 04:56:36.177 INFO [ClientCnxn]
[main-SendThread(223.prod:12913)] [application Session establishment complete
on server 223.prod/172.17.135.38:12913, sessionid = 0x134485fd7bcb26f,
negotiated timeout = 6000
application.log.2012-01-27.gz:2012/01/27 09:52:37.714 INFO [ClientCnxn]
[main-SendThread(223.prod:12913)] [application] Client session timed out,
have not heard from server in 9827ms for sessionid 0x134485fd7bcb26f, closing
socket connection and attempting reconnect
application.log.2012-01-27.gz:2012/01/27 09:52:38.191 INFO [ClientCnxn]
[main-SendThread(226.prod:12913)] [application] Unable to reconnect to
ZooKeeper service, session 0x134485fd7bcb26f has expired, closing socket
connection
On the leader zk, 225 -
zookeeper.log.2012-01-27-leader-225.gz:2012-01-27 09:52:34,010 - INFO
[SessionTracker:ZooKeeperServer@314] - Expiring session 0x134485fd7bcb26f,
timeout of 6000ms exceeded
zookeeper.log.2012-01-27-leader-225.gz:2012-01-27 09:52:34,010 - INFO
[ProcessThread:-1:PrepRequestProcessor@391] - Processed session termination
for sessionid: 0x134485fd7bcb26f
On the server, the client was initially connected to, 223 -
zookeeper.log.2012-01-26-223.gz:2012-01-26 04:56:36,173 - INFO
[CommitProcessor:1:NIOServerCnxn@1580] - Established session
0x134485fd7bcb26f with negotiated timeout 6000 for client /172.17.136.82:45020
zookeeper.log.2012-01-27-223.gz:2012-01-27 09:52:34,018 - INFO
[CommitProcessor:1:NIOServerCnxn@1435] - Closed socket connection for client
/172.17.136.82:45020 which had sessionid 0x134485fd7bcb26f
Here are the log snippets from 226, which is the server, the client
reconnected to, before getting session expired event -
2012-01-27 09:52:38,190 - INFO
[NIOServerCxn.Factory:0.0.0.0/0.0.0.0:12913:NIOServerCnxn@770] - Client
attempting to renew session 0x134485fd7bcb26f at /172.17.136.82:49367
2012-01-27 09:52:38,191 - INFO
[QuorumPeer:/0.0.0.0:12913:NIOServerCnxn@1573] - Invalid session
0x134485fd7bcb26f for client /172.17.136.82:49367, probably expired
2012-01-27 09:52:38,191 - INFO
[NIOServerCxn.Factory:0.0.0.0/0.0.0.0:12913:NIOServerCnxn@1435] - Closed
socket connection for client /172.17.136.82:49367 which had sessionid
0x134485fd7bcb26f
wchp output from 226, taken on 01/30 -
nnarkhed-ld:zk-cons-wchp-2012013000 nnarkhed$ grep 0x134485fd7bcb26f
*226.*wchp* | wc -l
3
wchp output from 223, taken on 01/30 -
nnarkhed-ld:zk-cons-wchp-2012013000 nnarkhed$ grep 0x134485fd7bcb26f
*223.*wchp* | wc -l
0
cons output from 223 and 226, taken on 01/30 -
nnarkhed-ld:zk-cons-wchp-2012013000 nnarkhed$ grep 0x134485fd7bcb26f
*226.*cons* | wc -l
0
nnarkhed-ld:zk-cons-wchp-2012013000 nnarkhed$ grep 0x134485fd7bcb26f
*223.*cons* | wc -l
0
So, what seems to have happened is that the client was able to re-register
the watches on the new server (226), after it got disconnected from 223,
inspite of having an expired session id.
In NIOServerCnxn, I saw that after suspecting that a session is expired, a
server removes the cnxn and its watches from its internal data structures.
But before that it allows more requests to be processed even if the session
is expired -
// Now that the session is ready we can start receiving packets
synchronized (this.factory) {
sk.selector().wakeup();
enableRecv();
}
} catch (Exception e) {
[jira] [Commented] (ZOOKEEPER-1382) Zookeeper server holds onto dead/expired session ids in the watch data structures
[ https://issues.apache.org/jira/browse/ZOOKEEPER-1382?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13592254#comment-13592254 ] Michael Morello commented on ZOOKEEPER-1382: It seems that the behavior of disableRecv() / enableRecv() has changed a bit in 3.5 : there is a new thread (SelectorThread) in charge of interest op updates and updates are processed in a non blocking fashion (updates are queued to be handled later by the SelectorThread, if i understand correctly it is more a throttle mechanism than something else). The unit test is no more relevant. If we want to fix the two branches (3.4 and 3.5) it is imho no more a good idea to rely on enableRecv(). May be it would be cleaner to introduce a new function ServerCnxn.setValidSession(boolean valid) that informs the implementation (NIOServerCnxn or NettyServerCnxn) that the session has been (re)validated and then allow subsequent messages to be processed. If you don't mind i will try to provide an other patch and a unit test for both branches. Zookeeper server holds onto dead/expired session ids in the watch data structures - Key: ZOOKEEPER-1382 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1382 Project: ZooKeeper Issue Type: Bug Components: server Affects Versions: 3.4.5 Reporter: Neha Narkhede Assignee: Neha Narkhede Priority: Critical Fix For: 3.4.6 Attachments: ZOOKEEPER-1382_3.3.4.patch, ZOOKEEPER-1382-branch-3.4.patch I've observed that zookeeper server holds onto expired session ids in the watcher data structures. The result is the wchp command reports session ids that cannot be found through cons/dump and those expired session ids sit there maybe until the server is restarted. Here are snippets from the client and the server logs that lead to this state, for one particular session id 0x134485fd7bcb26f - There are 4 servers in the zookeeper cluster - 223, 224, 225 (leader), 226 and I'm using ZkClient to connect to the cluster From the application log - application.log.2012-01-26-325.gz:2012/01/26 04:56:36.177 INFO [ClientCnxn] [main-SendThread(223.prod:12913)] [application Session establishment complete on server 223.prod/172.17.135.38:12913, sessionid = 0x134485fd7bcb26f, negotiated timeout = 6000 application.log.2012-01-27.gz:2012/01/27 09:52:37.714 INFO [ClientCnxn] [main-SendThread(223.prod:12913)] [application] Client session timed out, have not heard from server in 9827ms for sessionid 0x134485fd7bcb26f, closing socket connection and attempting reconnect application.log.2012-01-27.gz:2012/01/27 09:52:38.191 INFO [ClientCnxn] [main-SendThread(226.prod:12913)] [application] Unable to reconnect to ZooKeeper service, session 0x134485fd7bcb26f has expired, closing socket connection On the leader zk, 225 - zookeeper.log.2012-01-27-leader-225.gz:2012-01-27 09:52:34,010 - INFO [SessionTracker:ZooKeeperServer@314] - Expiring session 0x134485fd7bcb26f, timeout of 6000ms exceeded zookeeper.log.2012-01-27-leader-225.gz:2012-01-27 09:52:34,010 - INFO [ProcessThread:-1:PrepRequestProcessor@391] - Processed session termination for sessionid: 0x134485fd7bcb26f On the server, the client was initially connected to, 223 - zookeeper.log.2012-01-26-223.gz:2012-01-26 04:56:36,173 - INFO [CommitProcessor:1:NIOServerCnxn@1580] - Established session 0x134485fd7bcb26f with negotiated timeout 6000 for client /172.17.136.82:45020 zookeeper.log.2012-01-27-223.gz:2012-01-27 09:52:34,018 - INFO [CommitProcessor:1:NIOServerCnxn@1435] - Closed socket connection for client /172.17.136.82:45020 which had sessionid 0x134485fd7bcb26f Here are the log snippets from 226, which is the server, the client reconnected to, before getting session expired event - 2012-01-27 09:52:38,190 - INFO [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:12913:NIOServerCnxn@770] - Client attempting to renew session 0x134485fd7bcb26f at /172.17.136.82:49367 2012-01-27 09:52:38,191 - INFO [QuorumPeer:/0.0.0.0:12913:NIOServerCnxn@1573] - Invalid session 0x134485fd7bcb26f for client /172.17.136.82:49367, probably expired 2012-01-27 09:52:38,191 - INFO [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:12913:NIOServerCnxn@1435] - Closed socket connection for client /172.17.136.82:49367 which had sessionid 0x134485fd7bcb26f wchp output from 226, taken on 01/30 - nnarkhed-ld:zk-cons-wchp-2012013000 nnarkhed$ grep 0x134485fd7bcb26f *226.*wchp* | wc -l 3 wchp output from 223, taken on 01/30 - nnarkhed-ld:zk-cons-wchp-2012013000 nnarkhed$ grep 0x134485fd7bcb26f *223.*wchp* | wc -l 0 cons output from 223 and 226, taken on 01/30 - nnarkhed-ld:zk-cons-wchp-2012013000 nnarkhed$ grep
[jira] [Commented] (ZOOKEEPER-1382) Zookeeper server holds onto dead/expired session ids in the watch data structures
[ https://issues.apache.org/jira/browse/ZOOKEEPER-1382?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13596979#comment-13596979 ] Michael Morello commented on ZOOKEEPER-1382: My bad, I have not spend enough time on the new branch, you are right. The same fix could be applied. Nevertheless the unit test is no more relevant. I'll try to work on that. Zookeeper server holds onto dead/expired session ids in the watch data structures - Key: ZOOKEEPER-1382 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1382 Project: ZooKeeper Issue Type: Bug Components: server Affects Versions: 3.4.5 Reporter: Neha Narkhede Assignee: Neha Narkhede Priority: Critical Fix For: 3.4.6 Attachments: ZOOKEEPER-1382_3.3.4.patch, ZOOKEEPER-1382-branch-3.4.patch I've observed that zookeeper server holds onto expired session ids in the watcher data structures. The result is the wchp command reports session ids that cannot be found through cons/dump and those expired session ids sit there maybe until the server is restarted. Here are snippets from the client and the server logs that lead to this state, for one particular session id 0x134485fd7bcb26f - There are 4 servers in the zookeeper cluster - 223, 224, 225 (leader), 226 and I'm using ZkClient to connect to the cluster From the application log - application.log.2012-01-26-325.gz:2012/01/26 04:56:36.177 INFO [ClientCnxn] [main-SendThread(223.prod:12913)] [application Session establishment complete on server 223.prod/172.17.135.38:12913, sessionid = 0x134485fd7bcb26f, negotiated timeout = 6000 application.log.2012-01-27.gz:2012/01/27 09:52:37.714 INFO [ClientCnxn] [main-SendThread(223.prod:12913)] [application] Client session timed out, have not heard from server in 9827ms for sessionid 0x134485fd7bcb26f, closing socket connection and attempting reconnect application.log.2012-01-27.gz:2012/01/27 09:52:38.191 INFO [ClientCnxn] [main-SendThread(226.prod:12913)] [application] Unable to reconnect to ZooKeeper service, session 0x134485fd7bcb26f has expired, closing socket connection On the leader zk, 225 - zookeeper.log.2012-01-27-leader-225.gz:2012-01-27 09:52:34,010 - INFO [SessionTracker:ZooKeeperServer@314] - Expiring session 0x134485fd7bcb26f, timeout of 6000ms exceeded zookeeper.log.2012-01-27-leader-225.gz:2012-01-27 09:52:34,010 - INFO [ProcessThread:-1:PrepRequestProcessor@391] - Processed session termination for sessionid: 0x134485fd7bcb26f On the server, the client was initially connected to, 223 - zookeeper.log.2012-01-26-223.gz:2012-01-26 04:56:36,173 - INFO [CommitProcessor:1:NIOServerCnxn@1580] - Established session 0x134485fd7bcb26f with negotiated timeout 6000 for client /172.17.136.82:45020 zookeeper.log.2012-01-27-223.gz:2012-01-27 09:52:34,018 - INFO [CommitProcessor:1:NIOServerCnxn@1435] - Closed socket connection for client /172.17.136.82:45020 which had sessionid 0x134485fd7bcb26f Here are the log snippets from 226, which is the server, the client reconnected to, before getting session expired event - 2012-01-27 09:52:38,190 - INFO [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:12913:NIOServerCnxn@770] - Client attempting to renew session 0x134485fd7bcb26f at /172.17.136.82:49367 2012-01-27 09:52:38,191 - INFO [QuorumPeer:/0.0.0.0:12913:NIOServerCnxn@1573] - Invalid session 0x134485fd7bcb26f for client /172.17.136.82:49367, probably expired 2012-01-27 09:52:38,191 - INFO [NIOServerCxn.Factory:0.0.0.0/0.0.0.0:12913:NIOServerCnxn@1435] - Closed socket connection for client /172.17.136.82:49367 which had sessionid 0x134485fd7bcb26f wchp output from 226, taken on 01/30 - nnarkhed-ld:zk-cons-wchp-2012013000 nnarkhed$ grep 0x134485fd7bcb26f *226.*wchp* | wc -l 3 wchp output from 223, taken on 01/30 - nnarkhed-ld:zk-cons-wchp-2012013000 nnarkhed$ grep 0x134485fd7bcb26f *223.*wchp* | wc -l 0 cons output from 223 and 226, taken on 01/30 - nnarkhed-ld:zk-cons-wchp-2012013000 nnarkhed$ grep 0x134485fd7bcb26f *226.*cons* | wc -l 0 nnarkhed-ld:zk-cons-wchp-2012013000 nnarkhed$ grep 0x134485fd7bcb26f *223.*cons* | wc -l 0 So, what seems to have happened is that the client was able to re-register the watches on the new server (226), after it got disconnected from 223, inspite of having an expired session id. In NIOServerCnxn, I saw that after suspecting that a session is expired, a server removes the cnxn and its watches from its internal data structures. But before that it allows more requests to be processed even if the session is expired - // Now that the session is ready we can start receiving packets synchronized
