[GitHub] [pulsar] massakam opened a new pull request #5286: [pulsar-client-cpp] Fix memory leak caused by not being executed ClientConnection destructor

[GitBox <gi...@apache.org>]

massakam opened a new pull request #5286: [pulsar-client-cpp] Fix memory leak caused by not being executed ClientConnection destructor
URL: https://github.com/apache/pulsar/pull/5286
 
 
   ### Motivation
   
   Currently, closing a C++ Pulsar client object does not execute the destructor for the generated `ClientConnection` object. As a result, memory usage increases in applications that repeatedly create and close clients.
   
   This pull-request is a continuation of #5246.
   
   ### Modifications
   
   The reason why the `ClientConnection` destructor is not executed is that the reference count of the shared pointer does not become 0 even when the `ClientConnection` object is closed. As a result of the investigation, it was found that if the shared pointer `executor_` held by the `ClientConnection` object is reset, the reference count becomes 0 and the destructor is executed.
   
   ```diff
   --- a/pulsar-client-cpp/lib/ClientConnection.cc
   +++ b/pulsar-client-cpp/lib/ClientConnection.cc
   @@ -1385,6 +1385,10 @@ void ClientConnection::close() {
        if (tlsSocket_) {
            tlsSocket_->lowest_layer().close();
        }
   +
   +    if (executor_) {
   +        executor_.reset();
   +    }
    }
   
    bool ClientConnection::isClosed() const { return state_ == Disconnected; }
   ```
   
   However, with this fix alone, executing the following code causes an "Illegal instruction" error and the program crashes.
   https://gist.github.com/massakam/ebd169caff3db802eee5001b0d06c980
   
   The exact cause is unknown, but this issue doesn't seem to occur if closing `ClientConnection` before closing `ExecutorServiceProvider`. So, I changed the `ConnectionPool` destructor added in #5246 to the `close()` method and call it before closing `ExecutorServiceProvider`.

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