[Question posted by a user on YugabyteDB Community Slack]
We’re trying to do a postmortem on an issue we hit in our cluster. It looks like one of our 3 nodes went down and the other two were unable to process requests until it came back. Looking over the logs, I see this message a lot from both before and during the outage:
W0810 00:46:40.740047 3997211 leader_election.cc:285] T 00000000000000000000000000000000 P f65e3577ff4e42a3b935c36a99be1fb9 [CANDIDATE]: Term 7 pre-election: Tablet error from VoteRequest() call to peer df99aaa63d14414785aa9842fcf2fdc1: Invalid argument (yb/tserver/service_util.h:75): RequestConsensusVote: Wrong destination UUID requested. Local UUID: 55065b84a4df41ffac5841463871778a. Requested UUID: df99aaa63d14414785aa9842fcf2fdc1
I0810 00:46:40.740072 3997211 leader_election.cc:244] T 00000000000000000000000000000000 P f65e3577ff4e42a3b935c36a99be1fb9 [CANDIDATE]: Term 7 pre-election: Election decided. Result: candidate lost.
We, unfortunately, lost the logs from the node that went down due to a data loss issue on our side.Also, I’m actually still seeing the messages above even though the cluster has recovered so it looks like we’re still in a state.
What does this mean and does it prevent the cluster from electing a new leader?
The yb-master process recently running on prod-db-us-2 has a UUID of 55065b84a4df41ffac5841463871778a but the yb-master process running on prod-db-us-1 believes that the yb-master on prod-db-us-2 has a UUID of df99aaa63d14414785aa9842fcf2fdc1. This seems like a configuration issue.
My guess is that 55065b84a4df41ffac5841463871778a was originally df99aaa63d14414785aa9842fcf2fdc1. The UUID could change if the data directory is wiped.
You had a loss of data incident on prod-db-us-2 about a month and a half ago so that’s probably when the UUID changed.
Here’s the official documentation for replacing a failed master: https://docs.yugabyte.com/preview/troubleshoot/cluster/replace_master/
Alternatively, you could wipe 55065b84a4df41ffac5841463871778a and create a new yb-master using gflag instance_uuid_override to force it to initialize with uuid df99aaa63d14414785aa9842fcf2fdc1.
Related
[Question posted by a user on YugabyteDB Community Slack]
I am trying to read data in JSON format from CDC (YugabyteDB 2.13) for which I've used the following configuration:
connector.class=io.debezium.connector.yugabytedb.YugabyteDBConnector
database.streamid=88433e52543c4ecdb20934c6135beb3f
database.user=yugabyte
database.dbname=yugabyte
tasks.max=7
database.server.name=dbserver1
database.port=5433
database.master.addresses=<ip>:7100
database.hostname=<hostname>
database.password=yugabyte
table.include.list= sch.test
snapshot.mode=never
key.converter=org.apache.kafka.connect.json.JsonConverter
value.converter=org.apache.kafka.connect.json.JsonConverter
key.converter.schemas.enable=true
value.converter.schemas.enable=true
But I am unable to display data in JSON format. In fact the connector fails due
Schema for table 'sch.test' is missing (io.debezium.connector.yugabytedb.YugabyteDBChangeRecordEmitter:290)
[Worker-070086c4d98efddbd] [2022-04-12 11:04:15,978] ERROR [qorbital-test-json-msk|task-0] Producer failure (io.debezium.pipeline.ErrorHandler:31)
[Worker-070086c4d98efddbd] org.apache.kafka.connect.errors.ConnectException: Error while processing event at offset {transaction_id=null,
Is there a way I can fix it?
So the issue was with the version of YugabyteDB you were using (2.13.0), once it was released, there was a bug related to connector restarts which were causing a NullPointerException as the schema that is cached in the Debezium connector object was not persistent across the restart. So to fix the bug, we have added the logic to send the schema from the server-side every time there’s a restart or whenever the connector requests for the same, this will help in caching the schema and thus would resolve the NPE. Upgrading to a newer version will fix the issue.
Regarding Kafka-Zookeeper Security using DIGEST MD5 Authentication, I am trying to rotate/change credentials/password for both server(zookeeper) and client(kafka) jaas config file.
We have a 3 node cluster of 3 zookeepers and 3 kafka broker nodes with below jaas configuration file.
kafka.conf
org.apache.zookeeper.server.auth.DigestLoginModule required
username="super"
password="password";
};
zookeeper.conf
Server {
org.apache.zookeeper.server.auth.DigestLoginModule required
user_super="password";
};
To rotate we do a rolling restart of server(zookeeper) instances after updating the credential(password) and during the process of rolling restart after updating the same credential/password for super user for client(kafka instances) one at a time, we notice
[2019-06-15 17:17:38,929] INFO [ZooKeeperClient] Waiting until connected. (kafka.zookeeper.ZooKeeperClient)
[2019-06-15 17:17:38,929] INFO [ZooKeeperClient] Connected. (kafka.zookeeper.ZooKeeperClient)
these info level in server logs, which eventually results in unclean shutdown and restart of the broker which impacts the writes and reads for longer than expected. I have tried commenting requireClientAuthScheme=sasl in zookeeper zoo.cfg https://cwiki.apache.org/confluence/display/ZOOKEEPER/Client-Server+mutual+authentication to allow any clients authenticate to zookeeper but no success.
Also, alternative approach - tried to update the credential/password in jaas config file dynamically using sasl.jaas.config and do get the same exception documented in this jira (reference: https://issues.apache.org/jira/browse/KAFKA-8010).
can someone have any suggestions? Thanks in advance.
In Fauxton, I've setup a replication rule from a CouchDB v1.7.1 database to a new CouchDB v2.3.0 database.
The source does not have any authentication configured. The target does. I've added the username and password to the Job Configuration.
It looks like the replication got stuck somewhere in the process. 283.8 KB (433 documents) are present in the new database. The source contains about 18.7 MB (7215 docs) of data.
When restarting the database, I'm always getting the following error:
[error] 2019-02-17T17:29:45.959000Z nonode#nohost <0.602.0> --------
throw:{unauthorized,<<"unauthorized to access or create database
http://my-website.com/target-database-name/">>}:
Replication 5b4ee9ddc57bcad01e549ce43f5e31bc+continuous failed to
start "https://my-website.com/source-database-name/ "
-> "http://my-website.com/target-database-name/ " doc
<<"shards/00000000-1fffffff/_replicator.1550593615">>:<<"1e498a86ba8e3349692cc1c51a00037a">>
stack:[{couch_replicator_api_wrap,db_open,4,[{file,"src/couch_replicator_api_wrap.erl"},{line,114}]},{couch_replicator_scheduler_job,init_state,1,[{file,"src/couch_replicator_scheduler_job.erl"},{line,584}]}]
I'm not sure what is going on here. From the logs I understand there's an authorization issue. But the database is already present (hence, it has been replicated partially already).
What does this error mean and how can it be resolved?
The reason for this error is that the CouchDB v2.3.0 instance was being re-initialized on reboot. It required me to fill-in the cluster configuration again.
Therefore, the replication could not continue until I had the configuration re-applied.
The issue with having to re-apply the cluster configuration has been solved in another SO question.
While starting kudu-master, I am getting the below error and unable to start kudu cluster.
F0706 10:21:33.464331 27576 master_main.cc:71] Check failed: _s.ok() Bad status: Invalid argument: Unable to initialize catalog manager: Failed to initialize sys tables async: on-disk master list (hadoop-master:7051, slave2:7051, slave3:7051) and provided master list (:0) differ. Their symmetric difference is: :0, hadoop-master:7051, slave2:7051, slave3:7051
It is a cluster of 8 nodes and i have provided 3 masters as given below in master.gflagfile on master nodes.
--master_addresses=hadoop-master,slave2,slave3
TL;DR
If this is a new installation, working under the assumption that master ip addresses are correct, I believe the easiest solution is to
Stop kudu masters
Nuke the <kudu-data-dir>/master directory
Start kudu masters
Explanation
I believe the most common (if not only) cause of this error (Failed to initialize sys tables async: on-disk master list (hadoop-master:7051, slave2:7051, slave3:7051) and provided master list (:0) differ.) is when a kudu master node gets added incorrectly. The error suggests that kudu-master thinks it's running on a single node rather than 3-node cluster.
Maybe you did not intend to "add a node", but that's most likely what happened. I'm saying this because I had the same problem; after some googling and debugging, I discovered that during the installation, I started kudu-master before putting the correct IP address in master.gflagfile, so that kudu-master was spun up thinking it was running on a single node, not 3 node. Using steps above to clean install kudu-master again, my problem was solved.
I was trying to create a table inside Accumulo using the createtable command and found out that it was getting stuck. I waited for around 20 mins before cancelling the createtable command.
createtable test_table
I have one master and 2 tablet servers and found out that my master and one of the tablets died. I could not telnet to port 9997 of that particular tablet server and I could not even telnet to port 29999 (master.port.client in accumulo-site.xml). When I saw the tserver logs of the dead server, I saw the following entries.
2016-05-10 02:12:07,456 [zookeeper.DistributedWorkQueue] INFO : Got unexpected z
ookeeper event: None for /accumulo/be4f66be-1508-4314-9bff-888b56d9b0ce/recovery
2016-05-10 02:12:23,883 [zookeeper.ZooCache] WARN : Saw (possibly) transient exc
eption communicating with ZooKeeper, will retry
org.apache.zookeeper.KeeperException$SessionExpiredException: KeeperErrorCode =
Session expired for /accumulo/be4f66be-1508-4314-9bff-888b56d9b0ce/tables
at org.apache.zookeeper.KeeperException.create(KeeperException.java:127)
at org.apache.zookeeper.KeeperException.create(KeeperException.java:51)
at org.apache.zookeeper.ZooKeeper.getChildren(ZooKeeper.java:1472)
at org.apache.accumulo.fate.zookeeper.ZooCache$1.run(ZooCache.java:210)
at org.apache.accumulo.fate.zookeeper.ZooCache.retry(ZooCache.java:162)
at org.apache.accumulo.fate.zookeeper.ZooCache.getChildren(ZooCache.java
:221)
at org.apache.accumulo.core.client.impl.Tables.exists(Tables.java:142)
at org.apache.accumulo.server.tabletserver.LargestFirstMemoryManager.tab
leExists(LargestFirstMemoryManager.java:149)
at org.apache.accumulo.server.tabletserver.LargestFirstMemoryManager.get
MemoryManagementActions(LargestFirstMemoryManager.java:175)
at org.apache.accumulo.tserver.TabletServerResourceManager$MemoryManagem
entFramework.manageMemory(TabletServerResourceManager.java:408)
at org.apache.accumulo.tserver.TabletServerResourceManager$MemoryManagem
entFramework.access$400(TabletServerResourceManager.java:318)
at org.apache.accumulo.tserver.TabletServerResourceManager$MemoryManagem
entFramework$2.run(TabletServerResourceManager.java:346)
at org.apache.accumulo.fate.util.LoggingRunnable.run(LoggingRunnable.jav
a:35)
at java.lang.Thread.run(Thread.java:745)
2016-05-10 02:12:23,884 [zookeeper.ZooCache] WARN : Saw (possibly) transient exc
eption communicating with ZooKeeper, will retry
org.apache.zookeeper.KeeperException$SessionExpiredException: KeeperErrorCode =
Session expired for /accumulo/be4f66be-1508-4314-9bff-888b56d9b0ce/tables/!0/con
f/table.classpath.context
at org.apache.zookeeper.KeeperException.create(KeeperException.java:127)
at org.apache.zookeeper.KeeperException.create(KeeperException.java:51)
at org.apache.zookeeper.ZooKeeper.exists(ZooKeeper.java:1045)
at org.apache.accumulo.fate.zookeeper.ZooCache$2.run(ZooCache.java:264)
at org.apache.accumulo.fate.zookeeper.ZooCache.retry(ZooCache.java:162)
at org.apache.accumulo.fate.zookeeper.ZooCache.get(ZooCache.java:289)
at org.apache.accumulo.fate.zookeeper.ZooCache.get(ZooCache.java:238)
at org.apache.accumulo.server.conf.ZooCachePropertyAccessor.get(ZooCache
PropertyAccessor.java:117)
at org.apache.accumulo.server.conf.ZooCachePropertyAccessor.get(ZooCache
PropertyAccessor.java:103)
at org.apache.accumulo.server.conf.TableConfiguration.get(TableConfigura
tion.java:99)
at org.apache.accumulo.tserver.constraints.ConstraintChecker.classLoader
Changed(ConstraintChecker.java:93)
at org.apache.accumulo.tserver.tablet.Tablet.checkConstraints(Tablet.jav
a:1225)
at org.apache.accumulo.tserver.TabletServer$8.run(TabletServer.java:2848
)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:51
1)
at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.
access$301(ScheduledThreadPoolExecutor.java:180)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.
run(ScheduledThreadPoolExecutor.java:294)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.
java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor
.java:617)
at java.lang.Thread.run(Thread.java:745)
2016-05-10 02:12:23,887 [zookeeper.ZooReader] WARN : Saw (possibly) transient ex
ception communicating with ZooKeeper
org.apache.zookeeper.KeeperException$SessionExpiredException: KeeperErrorCode =
Session expired for /accumulo/be4f66be-1508-4314-9bff-888b56d9b0ce/tservers/accu
mulo.tablet.2:9997
at org.apache.zookeeper.KeeperException.create(KeeperException.java:127)
at org.apache.zookeeper.KeeperException.create(KeeperException.java:51)
at org.apache.zookeeper.ZooKeeper.exists(ZooKeeper.java:1045)
at org.apache.accumulo.fate.zookeeper.ZooReader.getStatus(ZooReader.java
:132)
at org.apache.accumulo.fate.zookeeper.ZooLock.process(ZooLock.java:383)
at org.apache.zookeeper.ClientCnxn$EventThread.processEvent(ClientCnxn.j
ava:522)
at org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:498)
2016-05-10 02:12:24,252 [watcher.MonitorLog4jWatcher] INFO : Changing monitor lo
g4j address to accumulo.master:4560
2016-05-10 02:12:24,252 [watcher.MonitorLog4jWatcher] INFO : Enabled log-forward
ing
Even the master server's logs had the same stacktrace. My zookeeper is running.
At first, I thought it was a disk issue. Maybe there was no space. But that was not the case. I ran the fsck on the accumulo instance.volumes and it returned the HEALTHY status.
Does anyone know what exactly happened and if possible, how to avoid it?
EDIT : Even the tracer_accumulo.master.log had the same stacktrace.
ZooKeeper session expirations occur when a thread inside the ZooKeeper client does not get run within the necessary time (by default, 30s) to maintain the session which is an in-memory state between ZooKeeper client and server. There is no single explanation for this, but many common culprits:
JVM garbage collection pauses in the client. Accumulo should log a warning if it experienced a pause.
Lack of CPU time. If the host itself is overburdened, Accumulo might not have the cycles to run all of the tasks it needs to in a timely manner.
Lack of sockets/filehandles, Accumulo could be trying to connect to ZooKeeper, but be unable to open new connections
ZooKeeper might be rate-limiting connections as a denial-of-service prevention. Check the zookeeper logs for errors about dropping/denying new connections from a specific IP, and, if you see these errors, consider increasing maxClientCnxns in zoo.cfg.