Is there a way to delete all the data from a topic or delete the topic before every run?
Apache KafkaApache ZookeeperApache Kafka Problem Overview
Is there a way to delete all the data from a topic or delete the topic before every run?
Can I modify the KafkaConfig.scala file to change the logRetentionHours
property? Is there a way the messages gets deleted as soon as the consumer reads it?
I am using producers to fetch the data from somewhere and sending the data to a particular topic where a consumer consumes, can I delete all the data from that topic on every run? I want only new data every time in the topic. Is there a way to reinitialize the topic somehow?
Apache Kafka Solutions
Solution 1 - Apache Kafka
As I mentioned here https://stackoverflow.com/questions/16284399/purge-kafka-queue/30833940#30833940:
Tested in Kafka 0.8.2, for the quick-start example: First, Add one line to server.properties file under config folder:
delete.topic.enable=true
then, you can run this command:
bin/kafka-topics.sh --zookeeper localhost:2181 --delete --topic test
Solution 2 - Apache Kafka
Don't think it is supported yet. Take a look at this JIRA issue "Add delete topic support".
To delete manually:
- Shutdown the cluster
- Clean kafka log dir (specified by the
log.dir
attribute in kafka config file ) as well the zookeeper data - Restart the cluster
For any given topic what you can do is
- Stop kafka
- Clean kafka log specific to partition, kafka stores its log file in a format of "logDir/topic-partition" so for a topic named "MyTopic" the log for partition id 0 will be stored in
/tmp/kafka-logs/MyTopic-0
where/tmp/kafka-logs
is specified by thelog.dir
attribute - Restart kafka
This is NOT
a good and recommended approach but it should work.
In the Kafka broker config file the log.retention.hours.per.topic
attribute is used to define The number of hours to keep a log file before deleting it for some specific topic
> Also, is there a way the messages gets deleted as soon as the consumer reads it?
From the Kafka Documentation :
> The Kafka cluster retains all published messages—whether or not they have been consumed—for a configurable period of time. For example if the log retention is set to two days, then for the two days after a message is published it is available for consumption, after which it will be discarded to free up space. Kafka's performance is effectively constant with respect to data size so retaining lots of data is not a problem. > >In fact the only metadata retained on a per-consumer basis is the position of the consumer in in the log, called the "offset". This offset is controlled by the consumer: normally a consumer will advance its offset linearly as it reads messages, but in fact the position is controlled by the consumer and it can consume messages in any order it likes. For example a consumer can reset to an older offset to reprocess.
For finding the start offset to read in Kafka 0.8 Simple Consumer example they say
> Kafka includes two constants to help, kafka.api.OffsetRequest.EarliestTime()
finds the beginning of the data in the logs and starts streaming from there, kafka.api.OffsetRequest.LatestTime()
will only stream new messages.
You can also find the example code there for managing the offset at your consumer end.
public static long getLastOffset(SimpleConsumer consumer, String topic, int partition,
long whichTime, String clientName) {
TopicAndPartition topicAndPartition = new TopicAndPartition(topic, partition);
Map<TopicAndPartition, PartitionOffsetRequestInfo> requestInfo = new HashMap<TopicAndPartition, PartitionOffsetRequestInfo>();
requestInfo.put(topicAndPartition, new PartitionOffsetRequestInfo(whichTime, 1));
kafka.javaapi.OffsetRequest request = new kafka.javaapi.OffsetRequest(requestInfo, kafka.api.OffsetRequest.CurrentVersion(),clientName);
OffsetResponse response = consumer.getOffsetsBefore(request);
if (response.hasError()) {
System.out.println("Error fetching data Offset Data the Broker. Reason: " + response.errorCode(topic, partition) );
return 0;
}
long[] offsets = response.offsets(topic, partition);
return offsets[0];
}
Solution 3 - Apache Kafka
Tested with kafka 0.10
1. stop zookeeper & Kafka server,
2. then go to 'kafka-logs' folder , there you will see list of kafka topic folders, delete folder with topic name
3. go to 'zookeeper-data' folder , delete data inside that.
4. start zookeeper & kafka server again.
Note : if you are deleting topic folder/s inside kafka-logs but not from zookeeper-data folder, then you will see topics are still there.
Solution 4 - Apache Kafka
Below are scripts for emptying and deleting a Kafka topic assuming localhost as the zookeeper server and Kafka_Home is set to the install directory:
The script below will empty a topic by setting its retention time to 1 second and then removing the configuration:
#!/bin/bash
echo "Enter name of topic to empty:"
read topicName
/$Kafka_Home/bin/kafka-configs --zookeeper localhost:2181 --alter --entity-type topics --entity-name $topicName --add-config retention.ms=1000
sleep 5
/$Kafka_Home/bin/kafka-configs --zookeeper localhost:2181 --alter --entity-type topics --entity-name $topicName --delete-config retention.ms
To fully delete topics you must stop any applicable kafka broker(s) and remove it's directory(s) from the kafka log dir (default: /tmp/kafka-logs) and then run this script to remove the topic from zookeeper. To verify it's been deleted from zookeeper the output of ls /brokers/topics should no longer include the topic:
#!/bin/bash
echo "Enter name of topic to delete from zookeeper:"
read topicName
/$Kafka_Home/bin/zookeeper-shell localhost:2181 <<EOF
rmr /brokers/topics/$topicName
ls /brokers/topics
quit
EOF
Solution 5 - Apache Kafka
As a dirty workaround, you can adjust per-topic runtime retention settings, e.g. bin/kafka-topics.sh --zookeeper localhost:2181 --alter --topic my_topic --config retention.bytes=1
(retention.bytes=0 might also work)
After a short while kafka should free the space. Not sure if this has any implications compared to re-creating the topic.
ps. Better bring retention settings back, once kafka done with cleaning.
You can also use retention.ms
to persist historical data
Solution 6 - Apache Kafka
We tried pretty much what the other answers are describing with moderate level of success. What really worked for us (Apache Kafka 0.8.1) is the class command
sh kafka-run-class.sh kafka.admin.DeleteTopicCommand --topic yourtopic --zookeeper localhost:2181
Solution 7 - Apache Kafka
For brew users
If you're using brew
like me and wasted a lot of time searching for the infamous kafka-logs
folder, fear no more. (and please do let me know if that works for you and multiple different versions of Homebrew, Kafka etc :) )
You're probably going to find it under:
Location:
/usr/local/var/lib/kafka-logs
How to actually find that path
(this is also helpful for basically every app you install through brew)
brew services list
> kafka started matbhz > /Users/matbhz/Library/LaunchAgents/homebrew.mxcl.kafka.plist
-
Open and read that
plist
you found above -
Find the line defining
server.properties
location open it, in my case:
/usr/local/etc/kafka/server.properties
- Look for the
log.dirs
line:
> log.dirs=/usr/local/var/lib/kafka-logs
-
Go to that location and delete the logs for the topics you wish
-
Restart Kafka with
brew services restart kafka
Solution 8 - Apache Kafka
All data about topics and its partitions are stored in tmp/kafka-logs/
. Moreover they are stored in a format topic-partionNumber
, so if you want to delete a topic newTopic
, you can:
- stop kafka
- delete the files
rm -rf /tmp/kafka-logs/newTopic-*
Solution 9 - Apache Kafka
As of kafka 2.3.0 version, there is an alternate way to soft deletion of Kafka (old approach are deprecated ).
Update retention.ms to 1 sec (1000ms) then set it again after a min, to default setting i.e 7 days (168 hours, 604,800,000 in ms )
Soft deletion:- (rentention.ms=1000) (using kafka-configs.sh)
bin/kafka-configs.sh --zookeeper 192.168.1.10:2181 --alter --entity-name kafka_topic3p3r --entity-type topics --add-config retention.ms=1000
Completed Updating config for entity: topic 'kafka_topic3p3r'.
Setting to default:- 7 days (168 hours , retention.ms= 604800000)
bin/kafka-configs.sh --zookeeper 192.168.1.10:2181 --alter --entity-name kafka_topic3p3r --entity-type topics --add-config retention.ms=604800000
Solution 10 - Apache Kafka
- Stop ZooKeeper and Kafka
- In server.properties, change log.retention.hours value. You can comment
log.retention.hours
and addlog.retention.ms=1000
. It would keep the record on Kafka Topic for only one second. - Start zookeeper and kafka.
- Check on consumer console. When I opened the console for the first time, record was there. But when I opened the console again, the record was removed.
- Later on, you can set the value of
log.retention.hours
to your desired figure.
Solution 11 - Apache Kafka
I use the utility below to cleanup after my integration test run.
It uses the latest AdminZkClient
api. The older api has been deprecated.
import javax.inject.Inject
import kafka.zk.{AdminZkClient, KafkaZkClient}
import org.apache.kafka.common.utils.Time
class ZookeeperUtils @Inject() (config: AppConfig) {
val testTopic = "users_1"
val zkHost = config.KafkaConfig.zkHost
val sessionTimeoutMs = 10 * 1000
val connectionTimeoutMs = 60 * 1000
val isSecure = false
val maxInFlightRequests = 10
val time: Time = Time.SYSTEM
def cleanupTopic(config: AppConfig) = {
val zkClient = KafkaZkClient.apply(zkHost, isSecure, sessionTimeoutMs, connectionTimeoutMs, maxInFlightRequests, time)
val zkUtils = new AdminZkClient(zkClient)
val pp = new Properties()
pp.setProperty("delete.retention.ms", "10")
pp.setProperty("file.delete.delay.ms", "1000")
zkUtils.changeTopicConfig(testTopic , pp)
// zkUtils.deleteTopic(testTopic)
println("Waiting for topic to be purged. Then reset to retain records for the run")
Thread.sleep(60000L)
val resetProps = new Properties()
resetProps.setProperty("delete.retention.ms", "3000000")
resetProps.setProperty("file.delete.delay.ms", "4000000")
zkUtils.changeTopicConfig(testTopic , resetProps)
}
}
There is an option delete topic. But, it marks the topic for deletion. Zookeeper later deletes the topic. Since this can be unpredictably long, I prefer the retention.ms approach
Solution 12 - Apache Kafka
In manually deleting a topic from a kafka cluster , you just might check this out https://github.com/darrenfu/bigdata/issues/6
A vital step missed a lot in most solution is in deleting the /config/topics/<topic_name>
in ZK.
Solution 13 - Apache Kafka
I use this script:
#!/bin/bash
topics=`kafka-topics --list --zookeeper zookeeper:2181`
for t in $topics; do
for p in retention.ms retention.bytes segment.ms segment.bytes; do
kafka-topics --zookeeper zookeeper:2181 --alter --topic $t --config ${p}=100
done
done
sleep 60
for t in $topics; do
for p in retention.ms retention.bytes segment.ms segment.bytes; do
kafka-topics --zookeeper zookeeper:2181 --alter --topic $t --delete-config ${p}
done
done
Solution 14 - Apache Kafka
There are two solutions to clean up topics data
-
Change the zookeeper dataDir path "dataDir=/dataPath" to some other value, delete kafka logs folder and restart zookeeper and kafka server
-
Run zkCleanup.sh from zookeeper server