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https://issues.apache.org/jira/browse/FLINK-18581?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17162096#comment-17162096
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Andrey Zagrebin edited comment on FLINK-18581 at 7/21/20, 4:31 PM:
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True, I overlooked the loop in ReferenceHandler.run.
{quote}1) Only support Java8 version later or equal than jdk8u72-b01. This
would entail that we throw an appropriate exception with a clear message saying
that one needs to update the java version. The main problem I see with this
approach is that other JVM implementation (other than OpenJDK) might not have
these private methods. Have we ever tried running Flink with a different JVM
implementation [~azagrebin]? Moreover, there is no guarantee that this method
won't disappear in some future version.
{quote}
I have Oracle JVM locally which I tried. Oracle jdk8u72 has the required method.
{quote}I think this is price we are paying for using internal JVM methods which
can change across minor versions and which is very unfortunate. Let's keep this
as a warning for the future and let's try to avoid it.
{quote}
I totally agree
{quote}2) Getting rid of the clean up mechanism which relies on internal JVM
methods and implement our own mechanism. This solution which involve a much
higher effort, though.
{quote}
This is hard to achieve our goal. We need to run release once the memory link
is ready for GC which can be detected only by GC. Or we have to change the
memory API/semantics somehow.
{quote}Maybe there is also some middle ground by trying to call
{{tryHandlerPending}} and if this method does not exist to fall back to
triggering the normal GC or some other mean to trigger the clean up.
{quote}
This is an option. We can wait a bit before calling GC to call it not so often
and give some time to the previous GC call. This is less performant and we can
output warning about the JVM version in this case. I can try it.
was (Author: azagrebin):
True, I overlooked the loop in ReferenceHandler.run.
{quote}1) Only support Java8 version later or equal than jdk8u72-b01. This
would entail that we throw an appropriate exception with a clear message saying
that one needs to update the java version. The main problem I see with this
approach is that other JVM implementation (other than OpenJDK) might not have
these private methods. Have we ever tried running Flink with a different JVM
implementation [~azagrebin]? Moreover, there is no guarantee that this method
won't disappear in some future version.
{quote}
I have Oracle JVM locally which I tried. I can check that Oracle jdk8u72 has
the required method.
{quote}I think this is price we are paying for using internal JVM methods which
can change across minor versions and which is very unfortunate. Let's keep this
as a warning for the future and let's try to avoid it.
{quote}
I totally agree
{quote}2) Getting rid of the clean up mechanism which relies on internal JVM
methods and implement our own mechanism. This solution which involve a much
higher effort, though.
{quote}
This is hard to achieve our goal. We need to run release once the memory link
is ready for GC which can be detected only by GC. Or we have to change the
memory API/semantics somehow.
{quote}Maybe there is also some middle ground by trying to call
{{tryHandlerPending}} and if this method does not exist to fall back to
triggering the normal GC or some other mean to trigger the clean up.
{quote}
This is an option. We can wait a bit before calling GC to call it not so often
and give some time to the previous GC call. This is less performant and we can
output warning about the JVM version in this case. I can try it.
> Cannot find GC cleaner with java version previous jdk8u72(-b01)
> ---------------------------------------------------------------
>
> Key: FLINK-18581
> URL: https://issues.apache.org/jira/browse/FLINK-18581
> Project: Flink
> Issue Type: Bug
> Components: Runtime / Coordination
> Affects Versions: 1.11.0
> Reporter: Xintong Song
> Priority: Critical
> Fix For: 1.12.0, 1.11.2
>
>
> {{JavaGcCleanerWrapper}} is looking for the package-private method
> {{Reference.tryHandlePending}} using reflection. However, the method is first
> introduced in the version jdk8u72(-b01). Therefore, if an older version JDK
> is used, the method cannot be found and Flink will fail.
> See also this [ML
> thread|http://apache-flink-user-mailing-list-archive.2336050.n4.nabble.com/Error-GC-Cleaner-Provider-Flink-1-11-0-td36565.html].
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