Add number of worker pthreads stuff into client.md

docs/cn/client.md

@@ -428,6 +428,10 @@ Controller的特点：
    - 同步RPC前Controller放栈上，出作用域后自行析构。注意异步RPC的Controller绝对不能放栈上，否则其析构时异步调用很可能还在进行中，从而引发未定义行为。
    - 异步RPC前new Controller，done中删除。
 
+## 线程数
+
+和大部分的RPC框架不同，brpc中并没有独立的Client线程池。所有Channel和Server通过[bthread](http://wiki.baidu.com/display/RPC/bthread)共享相同的线程池. 如果你的程序同样使用了brpc的server, 仅仅需要设置Server的线程数。 或者可以通过[gflags](http://wiki.baidu.com/display/RPC/flags)设置[-bthread_concurrency](http://brpc.baidu.com:8765/flags/bthread_concurrency)来设置全局的线程数.
+
 ## 超时
 
 **ChannelOptions.timeout_ms**是对应Channel上所有RPC的总超时，Controller.set_timeout_ms()可修改某次RPC的值。单位毫秒，默认值1秒，最大值2^31（约24天），-1表示一直等到回复或错误。

docs/en/client.md

@@ -430,6 +430,10 @@ Properties of Controller:
    - Put Controller on stack before synchronous RPC, be destructed when out of scope. Note that Controller of asynchronous RPC **must not** be put on stack, otherwise the RPC may still run when the Controller is being destructed and result in undefined behavior.
    - new Controller before asynchronous RPC, delete in done.
 
+## Number of worker pthreads
+
+There's **no** independent thread pool for client in brpc. All Channels and Servers share the same backing threads via [bthread](bthread.md).  Setting number of worker pthreads in Server works for Client as well if Server is in used. Or just specify the [gflag](flags.md) [-bthread_concurrency](brpc.baidu.com:8765/flags/bthread_concurrency) to set the global number of worker pthreads.
+
 ## Timeout
 
 **ChannelOptions.timeout_ms** is timeout in milliseconds for all RPCs via the Channel, Controller.set_timeout_ms() overrides value for one RPC. Default value is 1 second, Maximum value is 2^31 (about 24 days), -1 means wait indefinitely for response or connection error.