[1.3] cpu usage is too high when i start chip-tool interactive server

[jaggerwoo]

Reproduction steps

my system：

root@pi48g:~# uname -a
Linux pi48g 6.1.21-v8+ #1642 SMP PREEMPT Mon Apr  3 17:24:16 BST 2023 aarch64 GNU/Linux

when i run ./chip-tool interactive server, the cpu usage is nearly full

Bug prevalence

nil

GitHub hash of the SDK that was being used

nil

Platform

raspi

Platform Version(s)

No response

Type

Core SDK Performance Improvement

Anything else?

No response

[bzbarsky-apple]

Presumably this loop in WebSocketServer::Run (with all the time spent under lws_service per the profile):

    while (mRunning)
    {
        lws_service(context, -1);

        std::lock_guard<std::mutex> lock(gMutex);
        if (gMessageQueue.size())
        {
            lws_callback_on_writable(gWebSocketInstance);
        }
    }

[bzbarsky-apple]

Note that I tried changing that value to other values, but it still seems like all the time is taking in polling under lws_service, so this may just be a limitation of libwebsockets... Though I would have expected it to sleep until there is input.

[wilbur-se]

I just do bellow changes to WebSocketServer, may improve it.

index 46f9a63c9a..159649aada 100644
--- a/examples/common/websocket-server/WebSocketServer.cpp
+++ b/examples/common/websocket-server/WebSocketServer.cpp
@@ -95,7 +95,8 @@ void LogWebSocketCallbackReason(lws_callback_reasons reason)
         ChipLogDetail(chipTool, "LWS_CALLBACK_CLOSED");
         break;
     case LWS_CALLBACK_SERVER_WRITEABLE:
-        ChipLogDetail(chipTool, "LWS_CALLBACK_SERVER_WRITEABLE");
+        //ChipLogDetail(chipTool, "LWS_CALLBACK_SERVER_WRITEABLE");
         break;

@@ -179,7 +181,7 @@ CHIP_ERROR WebSocketServer::Run(chip::Optional<uint16_t> port, WebSocketServerDe

     while (mRunning)
     {
-        lws_service(context, -1);
+        lws_service(context, 0);

@@ -205,4 +214,8 @@ void WebSocketServer::Send(const char * msg)
 {
     std::lock_guard<std::mutex> lock(gMutex);
     gMessageQueue.push_back(msg);
+    if (gWebSocketInstance)
+    {
+        lws_callback_on_writable(gWebSocketInstance);
+    }
``` /