Hi,

Did you put the clickhouse JDBC driver on Flink main classpath (in lib folder) and not in user-jar - as described here: https://ci.apache.org/projects/flink/flink-docs-release-1.12/ops/debugging/debugging_classloading.html#unloading-of-dynamically-loaded-classes-in-user-code?

When we encountered Metaspace leaks recently, in quite a few cases it turned out that the problem was the JDBC driver in user classloder which was registered by DriverManager and caused classloader leak.


maciek


On 08.04.2021 11:42, ?????? wrote:
My application program looks like this. Does this structure has some problem?

public class StreamingJob {
public static void main(String[] args) throws Exception {
int i = 0;
while (i < 100) {
try {
StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
env.setRuntimeMode(RuntimeExecutionMode.BATCH);
env.setParallelism(Parallelism);

EnvironmentSettings bsSettings = EnvironmentSettings.newInstance().useBlinkPlanner()
.inStreamingMode().build();
StreamTableEnvironment bsTableEnv = StreamTableEnvironment.create(env, bsSettings);

bsTableEnv.executeSql("CREATE TEMPORARY TABLE xxxx");
Table t = bsTableEnv.sqlQuery(query);

DataStream<DataPoint> points = bsTableEnv.toAppendStream(t, DataPoint.class);

DataStream<StatisPoint> weightPoints = points.map();

DataStream<PredictPoint> predictPoints = weightPoints.keyBy()
.reduce().map();

// side output
final OutputTag<PredictPoint> outPutPredict = new OutputTag<PredictPoint>("predict") {
};

SingleOutputStreamOperator<PredictPoint> mainDataStream = predictPoints
.process();

DataStream<PredictPoint> exStream = mainDataStream.getSideOutput(outPutPredict);

?0?2 ?0?2 ?0?2 ?0?2 ?0?2 ?0?2 ?0?2 ?0?2 ?0?2 ?0?2 ?0?2 ?0?2 ?0?2 ?0?2 ?0?2 ?0?2 
?0?2 ?0?2 ?0?2 ?0?2 //write data to clickhouse
String insertIntoCKSql = "xxx";
mainDataStream.addSink(JdbcSink.sink(insertIntoCKSql, new CkSinkBuilder(),
new JdbcExecutionOptions.Builder().withBatchSize(CkBatchSize).build(),
new JdbcConnectionOptions.JdbcConnectionOptionsBuilder().withDriverName(CkDriverName)
.withUrl(CkUrl).withUsername(CkUser).withPassword(CkPassword).build()));

// write data to kafka
FlinkKafkaProducer<String> producer = new FlinkKafkaProducer<>();
exStream.map().addSink(producer);

env.execute("Prediction Program");
} catch (Exception e) {
e.printStackTrace();
}
i++;
Thread.sleep(window * 1000);
}
}
}



------------------?0?2?????????0?2------------------
*??????:* "Arvid Heise" <ar...@apache.org>;
*????????:*?0?22021??4??8??(??????) ????2:33
*??????:*?0?2"Yangze Guo"<karma...@gmail.com>;
*????:*?0?2"??????"<495635...@qq.com>;"user"<user@flink.apache.org>;"guowei.mgw"<guowei....@gmail.com>;"renqschn"<renqs...@gmail.com>;
*????:*?0?2Re: period batch job lead to OutOfMemoryError: Metaspace problem

Hi,

ChildFirstClassLoader are created (more or less) by application jar and seeing so many looks like a classloader leak to me. I'd expect you to see a new ChildFirstClassLoader popping up with each new job submission.

Can you check who is referencing the ChildFirstClassLoader transitively? Usually, it's some thread that is lingering around because some third party library is leaking threads etc.

OneInputStreamTask is legit and just indicates that you have a job running with 4 slots on that TM. It should not hold any dedicated metaspace memory.

On Thu, Apr 8, 2021 at 4:52 AM Yangze Guo <karma...@gmail.com <mailto:karma...@gmail.com>> wrote:

    I went through the JM & TM logs but could not find any valuable clue.
    The exception is actually thrown by kafka-producer-network-thread.
    Maybe @Qingsheng could also take a look?


    Best,
    Yangze Guo

    On Thu, Apr 8, 2021 at 10:39 AM ?????? <495635...@qq.com
    <mailto:495635...@qq.com>> wrote:
    >
    > I have configured to 512M, but problem still exist. Now the
    memory size is still 256M.
    > Attachments are TM and JM logs.
    >
    > Look forward to your reply.
    >
    > ------------------ ???????? ------------------
    > ??????: "Yangze Guo" <karma...@gmail.com
    <mailto:karma...@gmail.com>>;
    > ????????: 2021??4??6??(??????) ????6:35
    > ??????: "??????"<495635...@qq.com <mailto:495635...@qq.com>>;
    > ????: "user"<user@flink.apache.org
    <mailto:user@flink.apache.org>>;"guowei.mgw"<guowei....@gmail.com
    <mailto:guowei....@gmail.com>>;
    > ????: Re: period batch job lead to OutOfMemoryError: Metaspace
    problem
    >
    > > I have tried this method, but the problem still exist.
    > How much memory do you configure for it?
    >
    > > is 21 instances of
    "org.apache.flink.util.ChildFirstClassLoader" normal
    > Not quite sure about it. AFAIK, each job will have a classloader.
    > Multiple tasks of the same job in the same TM will share the same
    > classloader. The classloader will be removed if there is no more
    task
    > running on the TM. Classloader without reference will be finally
    > cleanup by GC. Could you share JM and TM logs for further analysis?
    > I'll also involve @Guowei Ma in this thread.
    >
    >
    > Best,
    > Yangze Guo
    >
    > On Tue, Apr 6, 2021 at 6:05 PM ?????? <495635...@qq.com
    <mailto:495635...@qq.com>> wrote:
    > >
    > > I have tried this method, but the problem still exist.
    > > by heap dump analysis, is 21 instances of
    "org.apache.flink.util.ChildFirstClassLoader" normal?
    > >
    > >
    > > ------------------ ???????? ------------------
    > > ??????: "Yangze Guo" <karma...@gmail.com
    <mailto:karma...@gmail.com>>;
    > > ????????: 2021??4??6??(??????) ????4:32
    > > ??????: "??????"<495635...@qq.com <mailto:495635...@qq.com>>;
    > > ????: "user"<user@flink.apache.org
    <mailto:user@flink.apache.org>>;
    > > ????: Re: period batch job lead to OutOfMemoryError: Metaspace
    problem
    > >
    > > I think you can try to increase the JVM metaspace option for
    > > TaskManagers through taskmanager.memory.jvm-metaspace.size. [1]
    > >
    > > [1]
    
https://ci.apache.org/projects/flink/flink-docs-master/docs/deployment/memory/mem_trouble/#outofmemoryerror-metaspace
    
<https://ci.apache.org/projects/flink/flink-docs-master/docs/deployment/memory/mem_trouble/#outofmemoryerror-metaspace>
    > >
    > > Best,
    > > Yangze Guo
    > >
    > > Best,
    > > Yangze Guo
    > >
    > >
    > > On Tue, Apr 6, 2021 at 4:22 PM ?????? <495635...@qq.com
    <mailto:495635...@qq.com>> wrote:
    > > >
    > > > batch job??
    > > > read data from s3 by sql??then by some operators and write
    data to clickhouse and kafka.
    > > > after some times, task-manager quit with OutOfMemoryError:
    Metaspace.
    > > >
    > > > env??
    > > > flink version??1.12.2
    > > > task-manager slot count: 5
    > > > deployment?? standalone kubernetes session ????
    > > > dependencies??
    > > >
    > > >?0?2 ?0?2 ?0?2<dependency>
    > > >
    > > > ?0?2<groupId>org.apache.flink</groupId>
    > > >
    > > > ?0?2<artifactId>flink-connector-kafka_2.11</artifactId>
    > > >
    > > > ?0?2<version>${flink.version}</version>
    > > >
    > > >?0?2 ?0?2 ?0?2</dependency>
    > > >
    > > >?0?2 ?0?2 ?0?2<dependency>
    > > >
    > > > ?0?2<groupId>com.google.code.gson</groupId>
    > > >
    > > > ?0?2<artifactId>gson</artifactId>
    > > >
    > > >?0?2 ?0?2 ?0?2 ?0?2<version>2.8.5</version>
    > > >
    > > >?0?2 ?0?2 ?0?2</dependency>
    > > >
    > > >?0?2 ?0?2 ?0?2<dependency>
    > > >
    > > > ?0?2<groupId>org.apache.flink</groupId>
    > > >
    > > > ?0?2<artifactId>flink-connector-jdbc_2.11</artifactId>
    > > >
    > > > ?0?2<version>${flink.version}</version>
    > > >
    > > >?0?2 ?0?2 ?0?2</dependency>
    > > >
    > > >?0?2 ?0?2 ?0?2<dependency>
    > > >
    > > > ?0?2<groupId>ru.yandex.clickhouse</groupId>
    > > >
    > > > ?0?2<artifactId>clickhouse-jdbc</artifactId>
    > > >
    > > >?0?2 ?0?2 ?0?2 ?0?2<version>0.3.0</version>
    > > >
    > > >?0?2 ?0?2 ?0?2</dependency>
    > > >
    > > >?0?2 ?0?2 ?0?2<dependency>
    > > >
    > > > ?0?2<groupId>org.apache.flink</groupId>
    > > >
    > > > ?0?2<artifactId>flink-parquet_2.11</artifactId>
    > > >
    > > > ?0?2<version>${flink.version}</version>
    > > >
    > > >?0?2 ?0?2 ?0?2</dependency>
    > > >
    > > >?0?2 ?0?2 ?0?2<dependency>
    > > >
    > > > <groupId>org.apache.flink</groupId>
    > > >
    > > > <artifactId>flink-json</artifactId>
    > > >
    > > > <version>${flink.version}</version>
    > > >
    > > >?0?2 ?0?2 ?0?2</dependency>
    > > >
    > > >
    > > > heap dump1:
    > > >
    > > > Leak Suspects
    > > >
    > > > System Overview
    > > >
    > > >?0?2 Leaks
    > > >
    > > >?0?2 Overview
    > > >
    > > >
    > > >?0?2 ?0?2Problem Suspect 1
    > > >
    > > > 21 instances of
    "org.apache.flink.util.ChildFirstClassLoader", loaded by
    "sun.misc.Launcher$AppClassLoader @ 0x73b2d42e0" occupy 29,656,880
    (41.16%) bytes.
    > > >
    > > > Biggest instances:
    > > >
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73ca2a1e8 -
    1,474,760 (2.05%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73d2af820 -
    1,474,168 (2.05%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73cdcaa10 -
    1,474,160 (2.05%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73cf6aab0 -
    1,474,160 (2.05%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73d1111d8 -
    1,474,160 (2.05%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73d2bb108 -
    1,474,128 (2.05%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73de202e0 -
    1,474,120 (2.05%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73dadc778 -
    1,474,112 (2.05%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73d5f70e8 -
    1,474,064 (2.05%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73d93aa38 -
    1,474,064 (2.05%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73e179638 -
    1,474,064 (2.05%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73dc80418 -
    1,474,056 (2.05%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73dfcda60 -
    1,474,056 (2.05%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73e4bcd38 -
    1,474,056 (2.05%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73d6006e8 -
    1,474,032 (2.05%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73c7d2ad8 -
    1,461,944 (2.03%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73ca1bb98 -
    1,460,752 (2.03%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73bf203f0 -
    1,460,744 (2.03%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73e3284a8 -
    1,445,232 (2.01%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73e65de00 -
    1,445,232 (2.01%) bytes.
    > > >
    > > >
    > > >
    > > > Keywords
    > > > org.apache.flink.util.ChildFirstClassLoader
    > > > sun.misc.Launcher$AppClassLoader @ 0x73b2d42e0
    > > > Details ?0?3
    > > >
    > > >?0?2 ?0?2Problem Suspect 2
    > > >
    > > > 34,407 instances of
    "org.apache.flink.core.memory.HybridMemorySegment", loaded by
    "sun.misc.Launcher$AppClassLoader @ 0x73b2d42e0" occupy 7,707,168
    (10.70%) bytes.
    > > >
    > > > Keywords
    > > > org.apache.flink.core.memory.HybridMemorySegment
    > > > sun.misc.Launcher$AppClassLoader @ 0x73b2d42e0
    > > >
    > > > Details ?0?3
    > > >
    > > >
    > > >
    > > > heap dump2:
    > > >
    > > > Leak Suspects
    > > >
    > > > System Overview
    > > >
    > > >?0?2 Leaks
    > > >
    > > >?0?2 Overview
    > > >
    > > >?0?2 ?0?2Problem Suspect 1
    > > >
    > > > 21 instances of
    "org.apache.flink.util.ChildFirstClassLoader", loaded by
    "sun.misc.Launcher$AppClassLoader @ 0x73b2d42e0" occupy 26,061,408
    (30.68%) bytes.
    > > >
    > > > Biggest instances:
    > > >
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73e9e9930 -
    1,474,224 (1.74%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73edce0b8 -
    1,474,224 (1.74%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73f1ad7d0 -
    1,474,168 (1.74%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73f3e5118 -
    1,474,168 (1.74%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73f5d3fe0 -
    1,474,168 (1.74%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73ebd8d28 -
    1,474,160 (1.74%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73efc00c0 -
    1,474,160 (1.74%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73e2251a8 -
    1,474,136 (1.74%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73cc24af0 -
    1,474,064 (1.74%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73cdca3e0 -
    1,474,064 (1.74%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73cf6f860 -
    1,474,064 (1.74%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73d114768 -
    1,474,064 (1.74%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73ca6f878 -
    1,474,056 (1.74%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73d2b7640 -
    1,474,056 (1.74%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73d2c1d80 -
    1,474,040 (1.74%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73c7e2868 -
    1,469,720 (1.73%) bytes.
    > > > org.apache.flink.util.ChildFirstClassLoader @ 0x73bf34a98 -
    1,460,808 (1.72%) bytes.
    > > >
    > > >
    > > >
    > > > Keywords
    > > > org.apache.flink.util.ChildFirstClassLoader
    > > > sun.misc.Launcher$AppClassLoader @ 0x73b2d42e0
    > > > Details ?0?3
    > > >
    > > >?0?2 ?0?2Problem Suspect 2
    > > >
    > > > 4 instances of
    "org.apache.flink.streaming.runtime.tasks.OneInputStreamTask",
    loaded by "sun.misc.Launcher$AppClassLoader @ 0x73b2d42e0" occupy
    11,644,200 (13.71%) bytes.
    > > >
    > > > Biggest instances:
    > > >
    > > > org.apache.flink.streaming.runtime.tasks.OneInputStreamTask
    @ 0x73e2d0cb0 - 4,364,536 (5.14%) bytes.
    > > > org.apache.flink.streaming.runtime.tasks.OneInputStreamTask
    @ 0x73d62fb88 - 3,643,576 (4.29%) bytes.
    > > > org.apache.flink.streaming.runtime.tasks.OneInputStreamTask
    @ 0x73dae0270 - 3,635,952 (4.28%) bytes.
    > > >
    > > >
    > > >
    > > > Keywords
    > > > sun.misc.Launcher$AppClassLoader @ 0x73b2d42e0
    > > > org.apache.flink.streaming.runtime.tasks.OneInputStreamTask
    > > > Details ?0?3
    > > >
    > > >

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