Fix netty ByteBuf reference counting #1711
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Netty was reporting "LEAK: ByteBuf.release() was not called", direct memory was growing unbounded. Remove unnecessary call to retain in h2 code. Fixes #1678
hawkw
approved these changes
Nov 22, 2017
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A better question is "why would this retain be necessary?". We're just moving a ByteBuf we already have a handle on into a new container. Or another question: "If this retain is appropriate, then were is the corresponding release?". |
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Correct me if I'm wrong, but we think this leak is likely the cause of #1690, right? Can we try to verify that this fixes that issue? |
adleong
approved these changes
Nov 24, 2017
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hawkw
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Dec 14, 2017
The Finagle `ByteBufAsBuf` converter wraps a Netty 4 `ByteBuf`, but does not support reference counting (see [this comment](https://github.com/twitter/finagle/blob/82d00660373582d6bfe56df8155b52528df36691/finagle-netty4/src/main/scala/com/twitter/finagle/netty4/ByteBufAsBuf.scala#L58-L61)). Therefore, when releasing a data frame whose content `ByteBuf` we `retain()` before wrapping it as a `Buf`, we must `release()` the underlying `ByteBuf`. This fixes the memory leak observed in #1678 without removing the call to `retain()` which was removed in #1711, which introduced a data corruption issue (#1728). If we `release()` the underlying `ByteBuf` after releasing the data frame, we can once again `retain()` it before converting to `Buf` without leaking, thus avoiding the data corruption caused by removing the `retain()`. Thanks to @vadimi for helping with this fix! Fixes #1728.
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Netty was reporting "LEAK: ByteBuf.release() was not called", direct
memory was growing unbounded.
Remove unnecessary call to retain in h2 code.
Verified netty leak messages go away with this fix.
Fixes #1678