James Roper created CASSANDRA-10984:
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Summary: Cassandra should not depend on netty-all
Key: CASSANDRA-10984
URL: https://issues.apache.org/jira/browse/CASSANDRA-10984
Project: Cassandra
Issue Type: Bug
Reporter: James Roper
Priority: Minor
netty-all is a jar that bundles all the individual netty dependencies for
convenience together for people trying out netty to get started quickly.
Serious projects like Cassandra should never ever ever use it, since it's a
recipe for classpath disasters.
To illustrate, I'm running Cassandra embedded in an app, and I get this error:
{noformat}
[JVM-1] java.lang.NoSuchMethodError:
io.netty.util.internal.PlatformDependent.newLongCounter()Lio/netty/util/internal/LongCounter;
[JVM-1] at io.netty.buffer.PoolArena.<init>(PoolArena.java:64)
~[netty-buffer-4.0.33.Final.jar:4.0.33.Final]
[JVM-1] at
io.netty.buffer.PoolArena$HeapArena.<init>(PoolArena.java:593)
~[netty-buffer-4.0.33.Final.jar:4.0.33.Final]
[JVM-1] at
io.netty.buffer.PooledByteBufAllocator.<init>(PooledByteBufAllocator.java:179)
~[netty-buffer-4.0.33.Final.jar:4.0.33.Final]
[JVM-1] at
io.netty.buffer.PooledByteBufAllocator.<init>(PooledByteBufAllocator.java:153)
~[netty-buffer-4.0.33.Final.jar:4.0.33.Final]
[JVM-1] at
io.netty.buffer.PooledByteBufAllocator.<init>(PooledByteBufAllocator.java:145)
~[netty-buffer-4.0.33.Final.jar:4.0.33.Final]
[JVM-1] at
io.netty.buffer.PooledByteBufAllocator.<clinit>(PooledByteBufAllocator.java:128)
~[netty-buffer-4.0.33.Final.jar:4.0.33.Final]
[JVM-1] at
org.apache.cassandra.transport.CBUtil.<clinit>(CBUtil.java:56)
~[cassandra-all-3.0.0.jar:3.0.0]
[JVM-1] at org.apache.cassandra.transport.Server.start(Server.java:134)
~[cassandra-all-3.0.0.jar:3.0.0]
{noformat}
{{PlatformDependent}} comes from netty-common, of which version 4.0.33 is on
the classpath, but it's also provided by netty-all, which has version 4.0.23
brought in by cassandra. By a fluke of classpath ordering, the classloader has
loaded the netty buffer classes from netty-buffer 4.0.33, but the
PlatformDependent class from netty-all 4.0.23, and these two versions are not
binary compatible, hence the linkage error.
Essentially to avoid these problems in serious projects, anyone that ever
brings in cassandra is going to have to exclude the netty dependency from it,
which is error prone, and when you get it wrong, due to the nature of classpath
ordering bugs, it might not be till you deploy to production that you actually
find out there's a problem.
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