inprocess: Avoid creating unnecessary threads #2108
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LGTM |
Implementations of ManagedClientTransport.start() are restricted from calling the passed listener until start() returns, in order to avoid reentrency problems with locks. For most transports this isn't a problem, because they need additional threads anyway. InProcess uses no additional threads naturally so ends up needing a thread just to notifyReady. Now transports can just return a Runnable that can be run after locks are dropped. This was originally intended to be a performance optimization, but the thread also causes nondeterminism because RPCs are delayed until notifyReady is called. So avoiding the thread reduces needless fakes during tests.
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@zhangkun83, do you think this should be backported to v1.0.x? I think we should, but I'm on the fence between doing it for v1.0.0 and v1.0.1. |
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Maybe 1.0.1? It may be a good idea to freeze the code for 1.0.0 at this moment, supposing 1.0.1 will happen soon after. |
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SGTM. Will backport after v1.0.0 is out. |
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Implementations of ManagedClientTransport.start() are restricted from
calling the passed listener until start() returns, in order to avoid
reentrency problems with locks. For most transports this isn't a
problem, because they need additional threads anyway. InProcess uses no
additional threads naturally so ends up needing a thread just to
notifyReady. Now transports can just return a Runnable that can be run
after locks are dropped.
This was originally intended to be a performance optimization, but the
thread also causes nondeterminism because RPCs are delayed until
notifyReady is called. So avoiding the thread reduces needless fakes
during tests.
I used ErrorProne to verify all calls to start() now handle the Runnable.