Logging Interceptor Interleaving

[eygraber]

I'm using HttpLoggingInterceptor from com.squareup.okhttp3:logging-interceptor:3.2.0 and I've noticed that when I make concurrent requests, the logging of the requests and responses are interleaved. I was able to fix this by providing a HttpLoggingInterceptor.Logger that adds synchronized to the log method. Was this left out of the library for performance purposes, or is it a bug?

HttpLoggingInterceptor loggingInterceptor = new HttpLoggingInterceptor(new HttpLoggingInterceptor.Logger() {
      @Override
      public synchronized void log(String message) {
        for (int i = 0, length = message.length(); i < length; i++) {
          int newline = message.indexOf('\n', i);
          newline = newline != -1 ? newline : length;
          do {
            int end = Math.min(newline, i + 4000);
            Log.d("OkHttp", message.substring(i, end));
            i = end;
          } while (i < newline);
        }
      }
    });
    loggingInterceptor.setLevel(HttpLoggingInterceptor.Level.BODY);

OkHttpClient client = new OkHttpClient.Builder()
        .
        .
        .
        .addInterceptor(loggingInterceptor) // this should be the last Interceptor added
        .build();

[swankjesse]

Synchronized here is a little bit dangerous. If your logger is slow for any reason, your network requests could queue up. And even with synchronized, we’re just as likely to interleave with OkHttp as we are with other processes on the device.

[eygraber]

It seemed to work out for when I have concurrent requests in flight, i.e. the logs are no longer interleaved. I know that it doesn't guarantee that it won't interleave with other logs, but it gets rid of the immediate issue of N concurrent requests interleaving their logs.

Because of the above, and the issue with logging potentially causing requests to queue up, is it safe to assume this is working as intended?

[swankjesse]

I think in any situation where the logging interceptor is showing many concurrent requests, our best solution is to recommend Charles Proxy or Stetho, rather than making the logging interceptor more powerful. It's worth the effort to set up these tools.