1ANRSystmHandle

sequenceDiagram

SystemServer->>SystemServer: AppNotResponding.run
activate SystemServer

Note right of SystemServer: 1.非异常场景下,统计进程信息,包括:
Note right of SystemServer: 发生ANR的进程,SystemServer进程,SurfaceFligner进程,CPU占用高的5个进程

Note right of SystemServer: 2.打印ANR顶部信息

被统计的进程->>被统计的进程: 虚拟机启动过程在SignalCatcher进行信号注册和监听(SIGQUIT)

SystemServer->>被统计的进程: 3.逐个向统计的进程发送SIGQUIT信号,通知dump进程信息

被统计的进程->>被统计的进程: TheadList::DumpForSigQuit
activate 被统计的进程
Note right of 被统计的进程: 遍历所有的Java线程和虚拟机线程,设置checkpoint,请求挂起suspend
deactivate 被统计的进程
被统计的进程->>被统计的进程: 所有线程挂起后，SignalCatcher线程开始遍历Dump各线程的堆栈和线程数据，结束之后再唤醒线程

SystemServer->>SystemServer: 监听管道并读取管道内容,写入Trace文件

deactivate SystemServer

private static void dumpStackTraces(String tracesFile, ArrayList<Integer> firstPids, ArrayList<Integer> nativePids, ArrayList<Integer> extraPids,
            boolean useTombstonedForJavaTraces) {
        ......
        ......
        //考虑到性能影响，一次dump最多持续20S，否则放弃后续进程直接结束
        remainingTime = 20 * 1000;
        try {
                ......
                //按照优先级依次获取各个进程trace日志
                int num = firstPids.size();
                for (int i = 0; i < num; i++) {
                    final long timeTaken;
                    if (useTombstonedForJavaTraces) {
                        timeTaken = dumpJavaTracesTombstoned(firstPids.get(i), tracesFile, remainingTime);
                    } else {
                        timeTaken = observer.dumpWithTimeout(firstPids.get(i), remainingTime);
                    }

                    remainingTime -= timeTaken;
                    if (remainingTime <= 0) {
                        //已经超时，则不再进行后续进程的dump操作
                        return;
                    }
                    }
                }
            }
            //按照优先级依次获取各个进程trace日志
                for (int pid : nativePids) {
                    final long nativeDumpTimeoutMs = Math.min(NATIVE_DUMP_TIMEOUT_MS, remainingTime);

                    final long start = SystemClock.elapsedRealtime();
                    Debug.dumpNativeBacktraceToFileTimeout(
                            pid, tracesFile, (int) (nativeDumpTimeoutMs / 1000));
                    final long timeTaken = SystemClock.elapsedRealtime() - start;

                    remainingTime -= timeTaken;
                    if (remainingTime <= 0) {
                                              //已经超时，则不再进行后续进程的dump操作
                        return;
                    }
                }
            }
            //按照优先级依次获取各个进程trace日志
                for (int pid : extraPids) {
                    final long timeTaken;
                    if (useTombstonedForJavaTraces) {
                        timeTaken = dumpJavaTracesTombstoned(pid, tracesFile, remainingTime);
                    } else {
                        timeTaken = observer.dumpWithTimeout(pid, remainingTime);
                    }

                    remainingTime -= timeTaken;
                    if (remainingTime <= 0) {
                        //已经超时，则不再进行后续进程的dump操作
                        return;
                    }
                }
            }
        }
        ......
    }