一饭庞、卡頓問題的幾種原因
復雜 UI 、圖文混排的繪制量過大熬荆;
在主線程上做網絡同步請求舟山;
在主線程做大量的 IO 操作;
運算量過大卤恳,CPU 持續(xù)高占用累盗;
死鎖和主子線程搶鎖。
二突琳、監(jiān)測卡頓的思路
監(jiān)測FPS:
FPS 是一秒顯示的幀數若债,也就是一秒內畫面變化數量。如果按照動畫片來說拆融,動畫片的 FPS 就是 24蠢琳,是達不到 60 滿幀的。也就是說镜豹,對于動畫片來說傲须,24 幀時雖然沒有 60 幀時流暢,但也已經是連貫的了趟脂,所以并不能說 24 幀時就算是卡住了泰讽。 由此可見,簡單地通過監(jiān)視 FPS 是很難確定是否會出現(xiàn)卡頓問題了昔期,所以我就果斷棄了通過監(jiān)視 FPS 來監(jiān)控卡頓的方案已卸。
RunLoop:
通過監(jiān)控 RunLoop 的狀態(tài)來判斷是否會出現(xiàn)卡頓。RunLoop原理這里就不再多說硼一,主要說方法累澡,首先明確loop的狀態(tài)有六個
typedef CF_OPTIONS(CFOptionFlags, CFRunLoopActivity) {
kCFRunLoopEntry , // 進入 loop
kCFRunLoopBeforeTimers , // 觸發(fā) Timer 回調
kCFRunLoopBeforeSources , // 觸發(fā) Source0 回調
kCFRunLoopBeforeWaiting , // 等待 mach_port 消息
kCFRunLoopAfterWaiting ), // 接收 mach_port 消息
kCFRunLoopExit , // 退出 loop
kCFRunLoopAllActivities // loop 所有狀態(tài)改變
}
我們需要監(jiān)測的狀態(tài)有兩個:RunLoop 在進入睡眠之前和喚醒后的兩個 loop 狀態(tài)定義的值,分別是 kCFRunLoopBeforeSources 和 kCFRunLoopAfterWaiting 欠动,也就是要觸發(fā) Source0 回調和接收 mach_port 消息兩個狀態(tài)永乌。
三、如何檢查卡頓
說下步驟:
創(chuàng)建一個 CFRunLoopObserverContext 觀察者具伍;
將創(chuàng)建好的觀察者 runLoopObserver 添加到主線程 RunLoop 的 common 模式下觀察翅雏;
創(chuàng)建一個持續(xù)的子線程專門用來監(jiān)控主線程的 RunLoop 狀態(tài);
一旦發(fā)現(xiàn)進入睡眠前的 kCFRunLoopBeforeSources 狀態(tài)人芽,或者喚醒后的狀態(tài) kCFRunLoopAfterWaiting望几,在設置的時間閾值內一直沒有變化,即可判定為卡頓萤厅;
dump 出堆棧的信息橄抹,從而進一步分析出具體是哪個方法的執(zhí)行時間過長靴迫;
上代碼:
#import <Foundation/Foundation.h>
@interface SMLagMonitor : NSObject
+ (instancetype)shareInstance;
- (void)beginMonitor; //開始監(jiān)視卡頓
- (void)endMonitor; //停止監(jiān)視卡頓
@end
#import "SMLagMonitor.h"
#import "SMCallStack.h"
#import "SMCPUMonitor.h"
@interface SMLagMonitor() {
int timeoutCount;
CFRunLoopObserverRef runLoopObserver;
@public
dispatch_semaphore_t dispatchSemaphore;
CFRunLoopActivity runLoopActivity;
}
@property (nonatomic, strong) NSTimer *cpuMonitorTimer;
@end
@implementation SMLagMonitor
#pragma mark - Interface
+ (instancetype)shareInstance {
static id instance = nil;
static dispatch_once_t dispatchOnce;
dispatch_once(&dispatchOnce, ^{
instance = [[self alloc] init];
});
return instance;
}
- (void)beginMonitor {
//監(jiān)測 CPU 消耗
self.cpuMonitorTimer = [NSTimer scheduledTimerWithTimeInterval:3
target:self
selector:@selector(updateCPUInfo)
userInfo:nil
repeats:YES];
//監(jiān)測卡頓
if (runLoopObserver) {
return;
}
dispatchSemaphore = dispatch_semaphore_create(0); //Dispatch Semaphore保證同步
//創(chuàng)建一個觀察者
CFRunLoopObserverContext context = {0,(__bridge void*)self,NULL,NULL};
runLoopObserver = CFRunLoopObserverCreate(kCFAllocatorDefault,
kCFRunLoopAllActivities,
YES,
0,
&runLoopObserverCallBack,
&context);
//將觀察者添加到主線程runloop的common模式下的觀察中
CFRunLoopAddObserver(CFRunLoopGetMain(), runLoopObserver, kCFRunLoopCommonModes);
//創(chuàng)建子線程監(jiān)控
dispatch_async(dispatch_get_global_queue(0, 0), ^{
//子線程開啟一個持續(xù)的loop用來進行監(jiān)控
while (YES) {
long semaphoreWait = dispatch_semaphore_wait(dispatchSemaphore, dispatch_time(DISPATCH_TIME_NOW, 20*NSEC_PER_MSEC));
if (semaphoreWait != 0) {
if (!runLoopObserver) {
timeoutCount = 0;
dispatchSemaphore = 0;
runLoopActivity = 0;
return;
}
//兩個runloop的狀態(tài),BeforeSources和AfterWaiting這兩個狀態(tài)區(qū)間時間能夠檢測到是否卡頓
if (runLoopActivity == kCFRunLoopBeforeSources || runLoopActivity == kCFRunLoopAfterWaiting) {
// 將堆棧信息上報服務器的代碼放到這里
//出現(xiàn)三次出結果
// if (++timeoutCount < 3) {
// continue;
// }
NSLog(@"monitor trigger");
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
// [SMCallStack callStackWithType:SMCallStackTypeAll];
});
} //end activity
}// end semaphore wait
timeoutCount = 0;
}// end while
});
}
- (void)endMonitor {
[self.cpuMonitorTimer invalidate];
if (!runLoopObserver) {
return;
}
CFRunLoopRemoveObserver(CFRunLoopGetMain(), runLoopObserver, kCFRunLoopCommonModes);
CFRelease(runLoopObserver);
runLoopObserver = NULL;
}
#pragma mark - Private
static void runLoopObserverCallBack(CFRunLoopObserverRef observer, CFRunLoopActivity activity, void *info){
SMLagMonitor *lagMonitor = (__bridge SMLagMonitor*)info;
lagMonitor->runLoopActivity = activity;
dispatch_semaphore_t semaphore = lagMonitor->dispatchSemaphore;
dispatch_semaphore_signal(semaphore);
}
- (void)updateCPUInfo {
thread_act_array_t threads;
mach_msg_type_number_t threadCount = 0;
const task_t thisTask = mach_task_self();
kern_return_t kr = task_threads(thisTask, &threads, &threadCount);
if (kr != KERN_SUCCESS) {
return;
}
for (int i = 0; i < threadCount; i++) {
thread_info_data_t threadInfo;
thread_basic_info_t threadBaseInfo;
mach_msg_type_number_t threadInfoCount = THREAD_INFO_MAX;
if (thread_info((thread_act_t)threads[i], THREAD_BASIC_INFO, (thread_info_t)threadInfo, &threadInfoCount) == KERN_SUCCESS) {
threadBaseInfo = (thread_basic_info_t)threadInfo;
if (!(threadBaseInfo->flags & TH_FLAGS_IDLE)) {
integer_t cpuUsage = threadBaseInfo->cpu_usage / 10;
if (cpuUsage > 70) {
//cup 消耗大于 70 時打印和記錄堆棧
NSString *reStr = smStackOfThread(threads[i]);
//記錄數據庫中
// [[[SMLagDB shareInstance] increaseWithStackString:reStr] subscribeNext:^(id x) {}];
NSLog(@"CPU useage overload thread stack:\n%@",reStr);
}
}
}
}
}
@end
使用楼誓,直接在APP didFinishLaunchingWithOptions 方法里面這樣寫:
[[SMLagMonitor shareInstance] beginMonitor];