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Posted to dev@brpc.apache.org by GitBox <gi...@apache.org> on 2020/09/08 04:19:01 UTC
[GitHub] [incubator-brpc] dyinnz opened a new issue #1229: Deadlock on std::recursive_mutex if bthread switched to another (real) thread while serving a RPC call
dyinnz opened a new issue #1229:
URL: https://github.com/apache/incubator-brpc/issues/1229
**Describe the bug (描述bug)**
**To Reproduce (复现方法)**
We may lock a std::recursive_mutex server times during a call. A deadlock occurs if bthread switched:
1. First, a bthread owns a std::recursive_mutex, and does something.
2. Then, this bthread switches to another (real) thread, and tries to lock again.
3. OK, here is a deadlock or a lock leaking. The std::recursive_mutex is hold by the old real thread, but the new thread would hang here if try to lock again.
**Expected behavior (期望行为)**
i thought that brpc could not support std::recursive_mutex after reading code and implementation. I ask whether and when this pr https://github.com/apache/incubator-brpc/pull/749 will be merged ? So we could replace std::recursive_mutex in our project.
**Versions (各种版本)**
OS: linux 4.14
Compiler: gcc 10.2.0, c++2a
brpc: n/a
protobuf: n/a
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[GitHub] [incubator-brpc] gydong commented on issue #1229: Deadlock on std::recursive_mutex if bthread switched to another (real) thread while serving a RPC call
Posted by GitBox <gi...@apache.org>.
gydong commented on issue #1229:
URL: https://github.com/apache/incubator-brpc/issues/1229#issuecomment-688637622
在brpc框架下，锁内RPC属于未定义行为，不管换成什么锁，问题还是一样
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[GitHub] [incubator-brpc] datatechboost edited a comment on issue #1229: Deadlock on std::recursive_mutex if bthread switched to another (real) thread while serving a RPC call
Posted by GitBox <gi...@apache.org>.
datatechboost edited a comment on issue #1229:
URL: https://github.com/apache/incubator-brpc/issues/1229#issuecomment-891492822
> > > 在brpc框架下，锁内RPC属于未定义行为，不管换成什么锁，问题还是一样
> >
> >
> > 你好，可以详细解释一下这个的原因吗？ 比如我们加了一个bthread_mutex锁然后发起rpc，rpc正常返回（或超时返回）后我们继续执行，为什么是不行的？ ps: 我使用时看起来那个rpc一直（按照早超时了）不返回，不知道是什么原因。
>
> 锁内rpc容易把所有worker都锁住，这样持锁的rpc将没有worker来执行导致锁永远无法释放
感谢你的回复，首先说明一下设计上锁内rpc确实并发度不好，进一步咨询是想理解的更深入。
使用bthread_mutex的话，worker是否不会被阻塞，如果不会阻塞是否有其它原因，我猜测是因为可运行任务的抢占有关，但是我自己没有不理顺。
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[GitHub] [incubator-brpc] luobuda commented on issue #1229: Deadlock on std::recursive_mutex if bthread switched to another (real) thread while serving a RPC call
Posted by GitBox <gi...@apache.org>.
luobuda commented on issue #1229:
URL: https://github.com/apache/incubator-brpc/issues/1229#issuecomment-890667319
锁内发rpc不管在哪都不该这么用吧
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[GitHub] [incubator-brpc] dyinnz commented on issue #1229: Deadlock on std::recursive_mutex if bthread switched to another (real) thread while serving a RPC call
Posted by GitBox <gi...@apache.org>.
dyinnz commented on issue #1229:
URL: https://github.com/apache/incubator-brpc/issues/1229#issuecomment-688659081
> 在brpc框架下，锁内RPC属于未定义行为，不管换成什么锁，问题还是一样
这里说的'锁内RPC'是指什么意思？我上面说的场景中，是 RPC 的被调用端，部分操作需要加锁，应该是 RPC内部用锁？
BTW，如果只是普通的 mutex，这里的行为应该是这个 bthread/pthread 被阻塞，只要 pthread worker 没有用完，这里应该不至于死锁吧？
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[GitHub] [incubator-brpc] datatechboost edited a comment on issue #1229: Deadlock on std::recursive_mutex if bthread switched to another (real) thread while serving a RPC call
Posted by GitBox <gi...@apache.org>.
datatechboost edited a comment on issue #1229:
URL: https://github.com/apache/incubator-brpc/issues/1229#issuecomment-891492822
> > > 在brpc框架下，锁内RPC属于未定义行为，不管换成什么锁，问题还是一样
> >
> >
> > 你好，可以详细解释一下这个的原因吗？ 比如我们加了一个bthread_mutex锁然后发起rpc，rpc正常返回（或超时返回）后我们继续执行，为什么是不行的？ ps: 我使用时看起来那个rpc一直（按照早超时了）不返回，不知道是什么原因。
>
> 锁内rpc容易把所有worker都锁住，这样持锁的rpc将没有worker来执行导致锁永远无法释放
感谢你的回复，首先说明一下设计上锁内rpc确实并发度不好，进一步咨询是想理解的更深入。
使用bthread_mutex的话，worker是否不会被阻塞，如果不会阻塞是否有其它原因，我猜测是因为可运行任务的抢占有关，但是我自己没有理顺。
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[GitHub] [incubator-brpc] datatechboost edited a comment on issue #1229: Deadlock on std::recursive_mutex if bthread switched to another (real) thread while serving a RPC call
Posted by GitBox <gi...@apache.org>.
datatechboost edited a comment on issue #1229:
URL: https://github.com/apache/incubator-brpc/issues/1229#issuecomment-890528631
> 在brpc框架下，锁内RPC属于未定义行为，不管换成什么锁，问题还是一样
你好，可以详细解释一下这个的原因吗？ 比如我们加了一个bthread_mutex锁然后发起rpc，rpc正常返回（或超时返回）后我们继续执行，为什么是不行的？ ps: 我使用时看起来那个rpc一直（按照早超时了）不返回，不知道是什么原因。
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[GitHub] [incubator-brpc] gydong commented on issue #1229: Deadlock on std::recursive_mutex if bthread switched to another (real) thread while serving a RPC call
Posted by GitBox <gi...@apache.org>.
gydong commented on issue #1229:
URL: https://github.com/apache/incubator-brpc/issues/1229#issuecomment-688687371
用STL中的mutex，不会导致bthread被切换到另一个系统线程中，因为系统线程会被阻塞，除非这个过程中调用了一些特定的阻塞函数（如bthread_sleep和butex_wait等等）或者做了同步rpc请求等等
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[GitHub] [incubator-brpc] datatechboost commented on issue #1229: Deadlock on std::recursive_mutex if bthread switched to another (real) thread while serving a RPC call
Posted by GitBox <gi...@apache.org>.
datatechboost commented on issue #1229:
URL: https://github.com/apache/incubator-brpc/issues/1229#issuecomment-890528631
> 在brpc框架下，锁内RPC属于未定义行为，不管换成什么锁，问题还是一样
你好，可以详细解释一下这个的原因吗？ 比如我们加了一个bthread_mutex锁然后发起rpc，rpc正常返回（或超时返回）后我们继续执行，为什么是不行的？
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[GitHub] [incubator-brpc] cdjingit commented on issue #1229: Deadlock on std::recursive_mutex if bthread switched to another (real) thread while serving a RPC call
Posted by GitBox <gi...@apache.org>.
cdjingit commented on issue #1229:
URL: https://github.com/apache/incubator-brpc/issues/1229#issuecomment-890760365
> > 在brpc框架下，锁内RPC属于未定义行为，不管换成什么锁，问题还是一样
>
> 你好，可以详细解释一下这个的原因吗？ 比如我们加了一个bthread_mutex锁然后发起rpc，rpc正常返回（或超时返回）后我们继续执行，为什么是不行的？ ps: 我使用时看起来那个rpc一直（按照早超时了）不返回，不知道是什么原因。
锁内rpc容易把所有worker都锁住，这样持锁的rpc将没有worker来执行导致锁永远无法释放
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[GitHub] [incubator-brpc] datatechboost commented on issue #1229: Deadlock on std::recursive_mutex if bthread switched to another (real) thread while serving a RPC call
Posted by GitBox <gi...@apache.org>.
datatechboost commented on issue #1229:
URL: https://github.com/apache/incubator-brpc/issues/1229#issuecomment-891492822
> > > 在brpc框架下，锁内RPC属于未定义行为，不管换成什么锁，问题还是一样
> >
> >
> > 你好，可以详细解释一下这个的原因吗？ 比如我们加了一个bthread_mutex锁然后发起rpc，rpc正常返回（或超时返回）后我们继续执行，为什么是不行的？ ps: 我使用时看起来那个rpc一直（按照早超时了）不返回，不知道是什么原因。
>
> 锁内rpc容易把所有worker都锁住，这样持锁的rpc将没有worker来执行导致锁永远无法释放
感谢你的回复，首先说明一下设计上锁内rpc确实并发度不好，想理解的更深入一层。
使用bthread_mutex的话，worker是否不会被阻塞，如果不会阻塞是否有其它原因，我猜测是因为可运行任务的抢占有关，但是我自己没有不理顺。
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