This may be caused by a jvm process can only load a so once.So a triky way is
to rename it。
发自我的 iPhone
> 在 2019年1月25日，上午7:12，Aaron Levin <aaronle...@stripe.com> 写道：
>
> Hi Ufuk,
>
> Update: I've pinned down the issue. It's multiple classloaders loading
> `libhadoop.so`:
>
> ```
> failed to load native hadoop with error: java.lang.UnsatisfiedLinkError:
> Native Library /usr/lib/libhadoop.so already loaded in another classloader
> ```
>
> I'm not quite sure what the solution is. Ideally flink would destroy a
> classloader when a job is canceled, but perhaps there's a jvm limitation
> there? Putting the libraries into `/usr/lib` or `/lib` does not work (as
> suggested by Chesnay in the ticket) as I get the same error. I might see if I
> can put a jar with `org.apache.hadoop.common.io.compress` in
> `/flink/install/lib` and then remove it from my jar. It's not an ideal
> solution but I can't think of anything else.
>
> Best,
>
> Aaron Levin
>
>> On Thu, Jan 24, 2019 at 12:18 PM Aaron Levin <aaronle...@stripe.com> wrote:
>> Hi Ufuk,
>>
>> I'm starting to believe the bug is much deeper than the originally reported
>> error because putting the libraries in `/usr/lib` or `/lib` does not work.
>> This morning I dug into why putting `libhadoop.so` into `/usr/lib` didn't
>> work, despite that being in the `java.library.path` at the call site of the
>> error. I wrote a small program to test the loading of native libraries, and
>> it was able to successfully load `libhadoop.so`. I'm very perplexed. Could
>> this be related to the way flink shades hadoop stuff?
>>
>> Here is my program and its output:
>>
>> ```
>> $ cat LibTest.scala
>> package com.redacted.flink
>>
>> object LibTest {
>> def main(args: Array[String]): Unit = {
>> val library = args(0)
>>
>> System.out.println(s"java.library.path=${System.getProperty("java.library.path")}")
>> System.out.println(s"Attempting to load $library")
>> System.out.flush()
>> System.loadLibrary(library)
>> System.out.println(s"Successfully loaded ")
>> System.out.flush()
>> }
>> ```
>>
>> I then tried running that on one of the task managers with `hadoop` as an
>> argument:
>>
>> ```
>> $ java -jar lib_test_deploy.jar hadoop
>> java.library.path=/usr/java/packages/lib/amd64:/usr/lib/x86_64-linux-gnu/jni:/lib/x86_64-linux-gnu:/usr/lib/x86_64-linux-gnu:/usr/lib/jni:/lib:/usr/lib
>> Attempting to load hadoop
>> Exception in thread "main" java.lang.UnsatisfiedLinkError: no hadoop in
>> java.library.path
>> at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1867)
>> at java.lang.Runtime.loadLibrary0(Runtime.java:870)
>> at java.lang.System.loadLibrary(System.java:1122)
>> at com.stripe.flink.LibTest$.main(LibTest.scala:11)
>> at com.stripe.flink.LibTest.main(LibTest.scala)
>> ```
>>
>> I then copied the native libraries into `/usr/lib/` and ran it again:
>>
>> ```
>> $ sudo cp /usr/local/hadoop/lib/native/libhadoop.so /usr/lib/
>> $ java -jar lib_test_deploy.jar hadoop
>> java.library.path=/usr/java/packages/lib/amd64:/usr/lib/x86_64-linux-gnu/jni:/lib/x86_64-linux-gnu:/usr/lib/x86_64-linux-gnu:/usr/lib/jni:/lib:/usr/lib
>> Attempting to load hadoop
>> Successfully loaded
>> ```
>>
>> Any ideas?
>>
>>> On Wed, Jan 23, 2019 at 7:13 PM Aaron Levin <aaronle...@stripe.com> wrote:
>>> Hi Ufuk,
>>>
>>> One more update: I tried copying all the hadoop native `.so` files (mainly
>>> `libhadoop.so`) into `/lib` and am I still experiencing the issue I
>>> reported. I also tried naively adding the `.so` files to the jar with the
>>> flink application and am still experiencing the issue I reported (however,
>>> I'm going to investigate this further as I might not have done it
>>> correctly).
>>>
>>> Best,
>>>
>>> Aaron Levin
>>>
>>>> On Wed, Jan 23, 2019 at 3:18 PM Aaron Levin <aaronle...@stripe.com> wrote:
>>>> Hi Ufuk,
>>>>
>>>> Two updates:
>>>>
>>>> 1. As suggested in the ticket, I naively copied the every `.so` in
>>>> `hadoop-3.0.0/lib/native/` into `/lib/` and this did not seem to help. My
>>>> knowledge of how shared libs get picked up is hazy, so I'm not sure if
>>>> blindly copying them like that should work. I did check what
>>>> `System.getProperty("java.library.path")` returns at the call-site and
>>>> it's:
>>>> java.library.path=/usr/java/packages/lib/amd64:/usr/lib/x86_64-linux-gnu/jni:/lib/x86_64-linux-gnu:/usr/lib/x86_64-linux-gnu:/usr/lib/jni:/lib:/usr/lib
>>>> 2. The exception I see comes from
>>>> `hadoop.util.NativeCodeLoader.buildSupportsSnappy` (stack-trace below).
>>>> This uses `System.loadLibrary("hadoop")`.
>>>>
>>>> [2019-01-23 19:52:33.081216] java.lang.UnsatisfiedLinkError:
>>>> org.apache.hadoop.util.NativeCodeLoader.buildSupportsSnappy()Z
>>>> [2019-01-23 19:52:33.081376] at
>>>> org.apache.hadoop.util.NativeCodeLoader.buildSupportsSnappy(Native Method)
>>>> [2019-01-23 19:52:33.081406] at
>>>> org.apache.hadoop.io.compress.SnappyCodec.checkNativeCodeLoaded(SnappyCodec.java:63)
>>>> [2019-01-23 19:52:33.081429] at
>>>> org.apache.hadoop.io.compress.SnappyCodec.getDecompressorType(SnappyCodec.java:195)
>>>> [2019-01-23 19:52:33.081457] at
>>>> org.apache.hadoop.io.compress.CodecPool.getDecompressor(CodecPool.java:181)
>>>> [2019-01-23 19:52:33.081494] at
>>>> org.apache.hadoop.io.SequenceFile$Reader.init(SequenceFile.java:2037)
>>>> [2019-01-23 19:52:33.081517] at
>>>> org.apache.hadoop.io.SequenceFile$Reader.initialize(SequenceFile.java:1923)
>>>> [2019-01-23 19:52:33.081549] at
>>>> org.apache.hadoop.io.SequenceFile$Reader.<init>(SequenceFile.java:1872)
>>>> ... (redacted) ...
>>>> [2019-01-23 19:52:33.081728] at
>>>> scala.collection.immutable.List.foreach(List.scala:392)
>>>> ... (redacted) ...
>>>> [2019-01-23 19:52:33.081832] at
>>>> org.apache.flink.streaming.api.operators.StreamSource.run(StreamSource.java:94)
>>>> [2019-01-23 19:52:33.081854] at
>>>> org.apache.flink.streaming.api.operators.StreamSource.run(StreamSource.java:58)
>>>> [2019-01-23 19:52:33.081882] at
>>>> org.apache.flink.streaming.runtime.tasks.SourceStreamTask.run(SourceStreamTask.java:99)
>>>> [2019-01-23 19:52:33.081904] at
>>>> org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:300)
>>>> [2019-01-23 19:52:33.081946] at
>>>> org.apache.flink.runtime.taskmanager.Task.run(Task.java:704)
>>>> [2019-01-23 19:52:33.081967] at java.lang.Thread.run(Thread.java:748)
>>>>
>>>>> On Tue, Jan 22, 2019 at 2:31 PM Aaron Levin <aaronle...@stripe.com> wrote:
>>>>> Hey Ufuk,
>>>>>
>>>>> So, I looked into this a little bit:
>>>>>
>>>>> 1. clarification: my issues are with the hadoop-related snappy libraries
>>>>> and not libsnappy itself (this is my bad for not being clearer, sorry!).
>>>>> I already have `libsnappy` on my classpath, but I am looking into
>>>>> including the hadoop snappy libraries.
>>>>> 2. exception: I don't see the class loading error. I'm going to try to
>>>>> put some more instrumentation and see if I can get a clearer stacktrace
>>>>> (right now I get an NPE on closing a sequence file in a finalizer - when
>>>>> I last logged the exception it was something deep in hadoop's snappy libs
>>>>> - I'll get clarification soon).
>>>>> 3. I'm looking into including hadoop's snappy libs in my jar and we'll
>>>>> see if that resolves the problem.
>>>>>
>>>>> Thanks again for your help!
>>>>>
>>>>> Best,
>>>>>
>>>>> Aaron Levin
>>>>>
>>>>>> On Tue, Jan 22, 2019 at 10:47 AM Aaron Levin <aaronle...@stripe.com>
>>>>>> wrote:
>>>>>> Hey,
>>>>>>
>>>>>> Thanks so much for the help! This is awesome. I'll start looking into
>>>>>> all of this right away and report back.
>>>>>>
>>>>>> Best,
>>>>>>
>>>>>> Aaron Levin
>>>>>>
>>>>>>> On Mon, Jan 21, 2019 at 5:16 PM Ufuk Celebi <u...@apache.org> wrote:
>>>>>>> Hey Aaron,
>>>>>>>
>>>>>>> sorry for the late reply.
>>>>>>>
>>>>>>> (1) I think I was able to reproduce this issue using snappy-java. I've
>>>>>>> filed a ticket here:
>>>>>>> https://issues.apache.org/jira/browse/FLINK-11402. Can you check the
>>>>>>> ticket description whether it's in line with what you are
>>>>>>> experiencing? Most importantly, do you see the same Exception being
>>>>>>> reported after cancelling and re-starting the job?
>>>>>>>
>>>>>>> (2) I don't think it's caused by the environment options not being
>>>>>>> picked up. You can check the head of the log files of the JobManager
>>>>>>> or TaskManager to verify that your provided option is picked up as
>>>>>>> expected. You should see something similar to this:
>>>>>>>
>>>>>>> 2019-01-21 22:53:49,863 INFO
>>>>>>> org.apache.flink.runtime.entrypoint.ClusterEntrypoint -
>>>>>>> --------------------------------------------------------------------------------
>>>>>>> 2019-01-21 22:53:49,864 INFO
>>>>>>> org.apache.flink.runtime.entrypoint.ClusterEntrypoint -
>>>>>>> Starting StandaloneSessionClusterEntrypoint (Version: 1.7.0,
>>>>>>> Rev:49da9f9, Date:28.11.2018 @ 17:59:06 UTC)
>>>>>>> ...
>>>>>>> 2019-01-21 22:53:49,865 INFO
>>>>>>> org.apache.flink.runtime.entrypoint.ClusterEntrypoint - JVM
>>>>>>> Options:
>>>>>>> 2019-01-21 22:53:49,865 INFO
>>>>>>> org.apache.flink.runtime.entrypoint.ClusterEntrypoint -
>>>>>>> -Xms1024m
>>>>>>> 2019-01-21 22:53:49,865 INFO
>>>>>>> org.apache.flink.runtime.entrypoint.ClusterEntrypoint -
>>>>>>> -Xmx1024m
>>>>>>> You are looking for this line ----> 2019-01-21 22:53:49,865 INFO
>>>>>>> org.apache.flink.runtime.entrypoint.ClusterEntrypoint -
>>>>>>> -Djava.library.path=/.../org/xerial/snappy/native/Mac/x86_64/ <----
>>>>>>> 2019-01-21 22:53:49,865 INFO
>>>>>>> org.apache.flink.runtime.entrypoint.ClusterEntrypoint -
>>>>>>> -Dlog.file=/.../flink-1.7.0/log/flink-standalonesession-0.local.log
>>>>>>> ...
>>>>>>> 2019-01-21 22:53:49,866 INFO
>>>>>>> org.apache.flink.runtime.entrypoint.ClusterEntrypoint -
>>>>>>> Program Arguments:
>>>>>>> 2019-01-21 22:53:49,866 INFO
>>>>>>> org.apache.flink.runtime.entrypoint.ClusterEntrypoint -
>>>>>>> --configDir
>>>>>>> 2019-01-21 22:53:49,866 INFO
>>>>>>> org.apache.flink.runtime.entrypoint.ClusterEntrypoint -
>>>>>>> /.../flink-1.7.0/conf
>>>>>>> 2019-01-21 22:53:49,866 INFO
>>>>>>> org.apache.flink.runtime.entrypoint.ClusterEntrypoint -
>>>>>>> --executionMode
>>>>>>> 2019-01-21 22:53:49,866 INFO
>>>>>>> org.apache.flink.runtime.entrypoint.ClusterEntrypoint -
>>>>>>> cluster
>>>>>>> ...
>>>>>>> 2019-01-21 22:53:49,866 INFO
>>>>>>> org.apache.flink.runtime.entrypoint.ClusterEntrypoint -
>>>>>>> --------------------------------------------------------------------------------
>>>>>>>
>>>>>>> Can you verify that you see the log messages as expected?
>>>>>>>
>>>>>>> (3) As noted FLINK-11402, is it possible to package the snappy library
>>>>>>> as part of your user code instead of loading the library via
>>>>>>> java.library.path? In my example, that seems to work fine.
>>>>>>>
>>>>>>> – Ufuk
>>>>>>>
>>>>>>> On Thu, Jan 17, 2019 at 5:53 PM Aaron Levin <aaronle...@stripe.com>
>>>>>>> wrote:
>>>>>>> >
>>>>>>> > Hello!
>>>>>>> >
>>>>>>> > *tl;dr*: settings in `env.java.opts` seem to stop having impact when
>>>>>>> > a job is canceled or fails and then is restarted (with or without
>>>>>>> > savepoint/checkpoints). If I restart the task-managers, the
>>>>>>> > `env.java.opts` seem to start having impact again and our job will
>>>>>>> > run without failure. More below.
>>>>>>> >
>>>>>>> > We use consume Snappy-compressed sequence files in our flink job.
>>>>>>> > This requires access to the hadoop native libraries. In our
>>>>>>> > `flink-conf.yaml` for both the task manager and the job manager, we
>>>>>>> > put:
>>>>>>> >
>>>>>>> > ```
>>>>>>> > env.java.opts: -Djava.library.path=/usr/local/hadoop/lib/native
>>>>>>> > ```
>>>>>>> >
>>>>>>> > If I launch our job on freshly-restarted task managers, the job
>>>>>>> > operates fine. If at some point I cancel the job or if the job
>>>>>>> > restarts for some other reason, the job will begin to crashloop
>>>>>>> > because it tries to open a Snappy-compressed file but doesn't have
>>>>>>> > access to the codec from the native hadoop libraries in
>>>>>>> > `/usr/local/hadoop/lib/native`. If I then restart the task manager
>>>>>>> > while the job is crashlooping, the job is start running without any
>>>>>>> > codec failures.
>>>>>>> >
>>>>>>> > The only reason I can conjure that would cause the Snappy compression
>>>>>>> > to fail is if the `env.java.opts` were not being passed through to
>>>>>>> > the job on restart for some reason.
>>>>>>> >
>>>>>>> > Does anyone know what's going on? Am I missing some additional
>>>>>>> > configuration? I really appreciate any help!
>>>>>>> >
>>>>>>> > About our setup:
>>>>>>> >
>>>>>>> > - Flink Version: 1.7.0
>>>>>>> > - Deployment: Standalone in HA
>>>>>>> > - Hadoop/S3 setup: we do *not* set `HADOOP_CLASSPATH`. We use Flink’s
>>>>>>> > shaded jars to access our files in S3. We do not use the
>>>>>>> > `bundled-with-hadoop` distribution of Flink.
>>>>>>> >
>>>>>>> > Best,
>>>>>>> >
>>>>>>> > Aaron Levin
