lorinlee opened a new issue #1449:
URL: https://github.com/apache/incubator-brpc/issues/1449
**Describe the bug (描述bug)**
In the implementation of `bthread_setspecific`, if the current bthread has
no KeyTable, a new KeyTable will be created. When the bthread ends, the created
KeyTable will not be destroyed but returned to a KeyTablePool, which causes a
memory leak. If we call `bthread_getspecific` before `bthread_setspecific`, the
memory leak will not happen because `bthread_getspecific` may borrow a KeyTable
from KeyTablePool and make `bthread_setspecific` reuse it.
This memory leak can be reproduced except these situations:
1. using `brpc::thread_local_data()` before `bthread_setspecific`.
`brpc::thread_local_data()` calls `bthread_getspecific` which may borrow a
KeyTable from KeyTablePool, after that, all `bthread_setspecific` will use this
KeyTabe instead of creating new one.
2. using LOG() before `bthread_setspecific`, the reason is the same as
above, the implementation of LOG() in brpc creates a LogStream which uses
`bthread_local`, and it calls `bthread_getspecific` at first.
3. calling `bthread_getspecific` before `bthread_setspecific`, also the same
as above.
**To Reproduce (复现方法)**
we can simply modify the `echo_c++` in `example` to reproduce this behavior,
the key code just like this.
```
brpc::ClosureGuard done_guard(done);
brpc::Controller* cntl =
static_cast<brpc::Controller*>(cntl_base);
if (bthread_setspecific(key1, static_cast<void*>(100)) != 0) {
//
}
```
and we can add log in `bthread_setspecific` to see if a KeyTable created or
not, the result is yes.
**Expected behavior (期望行为)**
users can just call `bthread_setspecific`, instead of calling
`bthread_getspecific` at first.
**Versions (各种版本)**
OS: Ubuntu 18.04.5 LTS
Compiler: g++ (Ubuntu 7.5.0-3ubuntu1~18.04) 7.5.0
brpc: master branch, commit id: 06505824def0e7bf23e548ff102e040363d31e38
protobuf: 3.0.0-9.1ubuntu1
**Additional context/screenshots (更多上下文/截图)**
The `bthread_setspecific` will create a new KeyTable and not borrow one from
KeyTablePool
The KeyTable will return to KeyTablePool when bthread ends.
The `bthread_getspecific` may borrow a KeyTable from KeyTablePool.
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