set tags workers unlimitedly

docs/cn/bthread_tagged_task_group.md

@@ -11,19 +11,19 @@
 
 ```c++
 服务端启动
-./echo_server -task_group_ntags 3 -tag1 0 -tag2 1 -bthread_concurrency 20 -bthread_min_concurrency 12 -event_dispatcher_num 1
+./echo_server -task_group_ntags 3 -tag1 0 -tag2 1 -bthread_concurrency 20 -bthread_min_concurrency 8 -event_dispatcher_num 1
 
 客户端启动
 ./echo_client -dummy_port 8888 -server "0.0.0.0:8002" -use_bthread true
 ./echo_client -dummy_port 8889 -server "0.0.0.0:8003" -use_bthread true
 ```
 
-FLAGS_bthread_concurrency为所有分组的线程数的上限，FLAGS_bthread_min_concurrency为所有分组的线程数的下限，FLAGS_event_dispatcher_num为单个分组中事件驱动器的数量。FLAGS_bthread_current_tag为将要修改的分组的tag值，FLAGS_bthread_concurrency_by_tag设置这个分组的线程数。
+FLAGS_bthread_concurrency为所有线程的数，FLAGS_bthread_min_concurrency为所有分组的线程数的下限，FLAGS_event_dispatcher_num为单个分组中事件驱动器的数量。FLAGS_bthread_current_tag为将要修改的分组的tag值，FLAGS_bthread_concurrency_by_tag设置这个分组的线程数。
 一般情况应用创建的bthread不需要设置bthread_attr_t的tag字段，创建的bthread会在当前tag上下文中执行；如果希望创建的bthread不在当前tag上下文中执行，可以设置bthread_attr_t的tag字段为希望的值，这么做会对性能有些损失，关键路径上应该避免这么做。
 
 Q：如何动态改变分组线程的数量？
 
-A：server的线程数最少为4个，后台任务线程数最少为2个，所以上面的例子中，FLAGS_bthread_concurrency最小值为4+4+2=10，再设置FLAGS_bthread_min_concurrency=FLAGS_bthread_concurrency，之后再把FLAGS_bthread_concurrency改大一些，之后再设置FLAGS_bthread_current_tag和FLAGS_bthread_concurrency_by_tag来改变某个分组的线程数。对于server，如果设置了ServerOption.bthread_tag，num_threads的含义是这个分组的线程数；如果没有设置（相当于没有启用分组，默认值为BTHREAD_TAG_INVALID）,num_thread的含义是所有分组的线程数。
+A：你可以根据你的服务更自由的设计你的每个分组的线程数，启动的时候会根据你设置的 bthread_concurrency 来初始化线程池，如果你设置了 bthread_min_concurrency，那么会根据 bthread_min_concurrency 来设置线程池，对于 server 来说，num_threads 就是该 tag 对应的 worker 数量。可以通过设置 FLAGS_bthread_current_tag 和 FLAGS_bthread_concurrency_by_tag 来改变某个分组的线程数。如果没有设置（相当于没有启用分组，默认值为BTHREAD_TAG_INVALID）,num_threads的含义是所有分组的 worker 总数。
 
 Q：不同分组之间有什么关系吗？
 

example/bthread_tag_echo_c++/server.cpp

@@ -29,8 +29,8 @@ DEFINE_int32(port2, 8003, "TCP Port of this server");
 DEFINE_int32(tag1, 0, "Server1 tag");
 DEFINE_int32(tag2, 1, "Server2 tag");
 DEFINE_int32(tag3, 2, "Background task tag");
-DEFINE_int32(num_threads1, 4, "Thread number of server1");
-DEFINE_int32(num_threads2, 4, "Thread number of server2");
+DEFINE_int32(num_threads1, 6, "Thread number of server1");
+DEFINE_int32(num_threads2, 16, "Thread number of server2");
 DEFINE_int32(idle_timeout_s, -1,
              "Connection will be closed if there is no "
              "read/write operations during the last `idle_timeout_s'");

src/brpc/server.cpp

@@ -1044,11 +1044,7 @@ int Server::StartInternal(const butil::EndPoint& endpoint,
         if (_options.num_threads < BTHREAD_MIN_CONCURRENCY) {
             _options.num_threads = BTHREAD_MIN_CONCURRENCY;
         }
-        if (original_bthread_tag == BTHREAD_TAG_INVALID) {
-            bthread_setconcurrency(_options.num_threads);
-        } else {
-            bthread_setconcurrency_by_tag(_options.num_threads, _options.bthread_tag);
-        }
+        bthread_setconcurrency_by_tag(_options.num_threads, _options.bthread_tag);
     }
 
     for (MethodMap::iterator it = _method_map.begin();

src/bthread/bthread.cpp

@@ -397,20 +397,22 @@ int bthread_setconcurrency_by_tag(int num, bthread_tag_t tag) {
     }
     auto c = bthread::get_or_new_task_control();
     BAIDU_SCOPED_LOCK(bthread::g_task_control_mutex);
-    auto ngroup = c->concurrency();
     auto tag_ngroup = c->concurrency(tag);
     auto add = num - tag_ngroup;
-    if (ngroup + add > bthread::FLAGS_bthread_concurrency) {
-        LOG(ERROR) << "Fail to set concurrency by tag " << tag
-                   << ", Total concurrency larger than bthread_concurrency";
-        return EPERM;
-    }
-    auto added = 0;
+
     if (add > 0) {
-        added = c->add_workers(add, tag);
+        auto added = c->add_workers(add, tag);
+        bthread::FLAGS_bthread_concurrency += added;
         return (add == added ? 0 : EPERM);
+
+    } else if (add < 0){
+        LOG(WARNING) << "Fail to set concurrency by tag: " << tag
+                     << ", tag concurrency must larger than old oncurrency. old concurrency: "
+                     << tag_ngroup << ", new concurrency: " << num;
+        return EPERM;
+    } else {
+        return 0;
     }
-    return (num == tag_ngroup ? 0 : EPERM);
 }
 
 int bthread_about_to_quit() {

test/bthread_setconcurrency_unittest.cpp

@@ -214,9 +214,11 @@ int concurrency_by_tag(int num) {
 
 TEST(BthreadTest, concurrency_by_tag) {
     ASSERT_EQ(concurrency_by_tag(1), false);
-    auto con = bthread_getconcurrency_by_tag(0);
+    auto tag_con = bthread_getconcurrency_by_tag(0);
+    auto con = bthread_getconcurrency();
     ASSERT_EQ(concurrency_by_tag(con), true);
-    ASSERT_EQ(concurrency_by_tag(con + 1), false);
+    ASSERT_EQ(concurrency_by_tag(con + 1), true);
+    ASSERT_EQ(bthread_getconcurrency(), con+1);
     bthread_setconcurrency(con + 1);
     ASSERT_EQ(concurrency_by_tag(con + 1), true);
 }