Input dispatching timed out

Question

Input dispatching timed out (Waiting to send non-key event because the touched window has not finished processing certain input events that were delivered to it over 500.0ms ago. Wait queue length: 16. Wait queue head age: 5548.9ms.)

I'm getting this strange ANR-report from several users. Unfortunately, I have very limited knowledge about ANR-reports, and I'm hoping that someone can help me to understand what the cause of this could be

Code :

record.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                synchronized (this){
                    startService(new Intent(ChatActivity.this,AudioRecorderService.class));
                }
            }
        });

        stop.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                stopService(new Intent(ChatActivity.this,AudioRecorderService.class));
            }
        });