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Posted to dev@tomcat.apache.org by bu...@apache.org on 2019/12/20 12:51:01 UTC
[Bug 64023] New: Session serialization does not support values that
(de)serialize to null
https://bz.apache.org/bugzilla/show_bug.cgi?id=64023
Bug ID: 64023
Summary: Session serialization does not support values that
(de)serialize to null
Product: Tomcat 9
Version: unspecified
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P2
Component: Cluster
Assignee: dev@tomcat.apache.org
Reporter: apache@nospam.obeliks.de
Target Milestone: -----
For caching purposes, we put some attributes in the session that are not
supposed to be distributed to backup nodes. We wanted to keep the webapp
distributable, and exclude these values explicitly from serialization, by
wrapping them in a serialization proxy that serializes to null (using
writeReplace).
While null values in the session are excluded from serialization in the first
place, null values returned from deserialization cause a NullPointerException
when the object is put into the ConcurrentHashMap:
> java.lang.NullPointerException
> at java.base/java.util.concurrent.ConcurrentHashMap.putVal(ConcurrentHashMap.java:1011)
> at java.base/java.util.concurrent.ConcurrentHashMap.put(ConcurrentHashMap.java:1006)
> at org.apache.catalina.ha.session.DeltaSession.doReadObject(DeltaSession.java:849)
> at org.apache.catalina.ha.session.DeltaSession.readObjectData(DeltaSession.java:618)
> at org.apache.catalina.ha.session.DeltaSession.readExternal(DeltaSession.java:593)
> at java.base/java.io.ObjectInputStream.readExternalData(ObjectInputStream.java:2136)
> at java.base/java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:2085)
> at java.base/java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1594)
> at java.base/java.io.ObjectInputStream.readObject(ObjectInputStream.java:430)
> at org.apache.catalina.tribes.io.XByteBuffer.deserialize(XByteBuffer.java:560)
> at org.apache.catalina.tribes.tipis.AbstractReplicatedMap$MapMessage.value(AbstractReplicatedMap.java:1507)
> at org.apache.catalina.tribes.tipis.AbstractReplicatedMap$MapMessage.deserialize(AbstractReplicatedMap.java:1465)
> at org.apache.catalina.tribes.tipis.AbstractReplicatedMap.messageReceived(AbstractReplicatedMap.java:663)
> at org.apache.catalina.tribes.group.GroupChannel.messageReceived(GroupChannel.java:336)
> at org.apache.catalina.tribes.group.ChannelInterceptorBase.messageReceived(ChannelInterceptorBase.java:91)
> at org.apache.catalina.tribes.group.interceptors.TcpFailureDetector.messageReceived(TcpFailureDetector.java:117)
> at org.apache.catalina.tribes.group.ChannelInterceptorBase.messageReceived(ChannelInterceptorBase.java:91)
> at org.apache.catalina.tribes.group.ChannelInterceptorBase.messageReceived(ChannelInterceptorBase.java:91)
> at org.apache.catalina.tribes.group.interceptors.ThroughputInterceptor.messageReceived(ThroughputInterceptor.java:86)
> at org.apache.catalina.tribes.group.ChannelInterceptorBase.messageReceived(ChannelInterceptorBase.java:91)
> at org.apache.catalina.tribes.group.ChannelCoordinator.messageReceived(ChannelCoordinator.java:274)
> at org.apache.catalina.tribes.transport.ReceiverBase.messageDataReceived(ReceiverBase.java:261)
> at org.apache.catalina.tribes.transport.nio.NioReplicationTask.drainChannel(NioReplicationTask.java:213)
> at org.apache.catalina.tribes.transport.nio.NioReplicationTask.run(NioReplicationTask.java:101)
> at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
> at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
> at java.base/java.lang.Thread.run(Thread.java:834)
While this might be an unconventional solution, it should be possible to have
null values in the object stream. A simple null-check after deserialization (in
both DeltaSession and StandardSession) looks sufficient.
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[Bug 64023] Session serialization does not support values that
(de)serialize to null
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=64023
--- Comment #3 from Christopher Schultz <ch...@christopherschultz.net> ---
Gotcha. I have a patch for this ready to go that I'll attach to the bugin case
you want to build your own for testing.
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[Bug 64023] Session serialization does not support values that
(de)serialize to null
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=64023
Christopher Schultz <ch...@christopherschultz.net> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |FIXED
--- Comment #6 from Christopher Schultz <ch...@christopherschultz.net> ---
(In reply to Christopher Schultz from comment #5)
> [...] there is no sense in writing the null-valued attribute to the
> serialized session, ever.
... except that in your case, it's writeReplace which is causing the null to be
written. There is no way for the session manager to know that will happen
without speculatively writing every session value to a scratch-area before
writing the object to the real output stream. This could be very expensive, so
it's best to simply leave the nulls in the serialized output.
Fixed in 9f98e7126a26283c9cc260232fd3fbd59900ef29 for 9.0.31.
Fixed in 50dacc525502387a326c3f47de53c0742b8a478b for 8.5.51.
Fixed in 9f98e7126a26283c9cc260232fd3fbd59900ef29 for Tomcat 7.0.100.
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[Bug 64023] Session serialization does not support values that
(de)serialize to null
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=64023
--- Comment #1 from Christopher Schultz <ch...@christopherschultz.net> ---
We'll look at this, as this should not fail, but there is another way to fix
this perhaps faster: use a wrapper object that has a single transient member
instead of writing null in writereplace().
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[Bug 64023] Session serialization does not support values that
(de)serialize to null
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=64023
--- Comment #5 from Christopher Schultz <ch...@christopherschultz.net> ---
Fixed in d9f243aa49.
I'm leaving this open because I think it makes sense to avoid serializing the
null values in the first place. Having the null-check in the deserialization
process is a good sanity check, anyways, but there is no sense in writing the
null-valued attribute to the serialized session, ever.
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[Bug 64023] Session serialization does not support values that
(de)serialize to null
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=64023
--- Comment #2 from Bernhard Frauendienst <ap...@nospam.obeliks.de> ---
I'm afraid that won't help, because the attribute in question belongs to a
session-scoped spring bean, and I need the session to contain null in order for
the factory method to be invoked anew after session migration.
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[Bug 64023] Session serialization does not support values that
(de)serialize to null
Posted by bu...@apache.org.
https://bz.apache.org/bugzilla/show_bug.cgi?id=64023
--- Comment #4 from Christopher Schultz <ch...@christopherschultz.net> ---
Created attachment 36926
--> https://bz.apache.org/bugzilla/attachment.cgi?id=36926&action=edit
Don't put null-valued attributes into the session attributes when deserializing
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