Download Timer Windows 10

This topic describes how to create, identify, set, and delete timers. An application uses a timer to schedule an event for a window after a specified time has elapsed. Each time the specified interval (or time-out value) for a timer elapses, the system notifies the window associated with the timer. Because a timer's accuracy depends on the system clock rate and how often the application retrieves messages from the message queue, the time-out value is only approximate.

Applications create timers by using the SetTimer function. A new timer starts timing the interval as soon as it is created. An application can change a timer's time-out value by using SetTimer and can destroy a timer by using the KillTimer function. To use system resources efficiently, applications should destroy timers that are no longer necessary.

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Each timer has a unique identifier. When creating a timer, an application can either specify an identifier or have the system create a unique value. The first parameter of a WM_TIMER message contains the identifier of the timer that posted the message.

If you specify a window handle in the call to SetTimer, the application associates the timer with that window. Whenever the time-out value for the timer elapses, the system posts a WM_TIMER message to the window associated with the timer. If no window handle is specified in the call to SetTimer, the application that created the timer must monitor its message queue for WM_TIMER messages and dispatch them to the appropriate window.

The QueryPerformanceCounter function retrieves the current value of the high-resolution performance counter. By calling this function at the beginning and end of a section of code, an application essentially uses the counter as a high-resolution timer. For example, suppose that QueryPerformanceFrequency indicates that the frequency of the high-resolution performance counter is 50,000 counts per second. If the application calls QueryPerformanceCounter immediately before and immediately after the section of code to be timed, the counter values might be 1500 counts and 3500 counts, respectively. These values would indicate that .04 seconds (2000 counts) elapsed while the code executed.

A waitable timer object is a synchronization object whose state is set to signaled when the specified due time arrives. There are two types of waitable timers that can be created: manual-reset and synchronization. A timer of either type can also be a periodic timer.

A thread uses the CreateWaitableTimer or CreateWaitableTimerEx function to create a timer object. The creating thread specifies whether the timer is a manual-reset timer or a synchronization timer. The creating thread can specify a name for the timer object. Threads in other processes can open a handle to an existing timer by specifying its name in a call to the OpenWaitableTimer function. Any thread with a handle to a timer object can use one of the wait functions to wait for the timer state to be set to signaled.

It works for some time (like 10-15 days) then it stops. I mean the service shows as running, but it does not do anything. I make some logging and the problem can be the timer, because after the interval it does not call the tickTack_Elapsed function.

I was thinking about rewrite it without a timer, using an endless loop, which stops the processing for the amount of time I set up. This is also not an elegant solution and I think it can have some side effects regarding memory.

I edited both services. One got a nice try-catch everywhere and more logging. The second got a timer-recreation on a regular basis. None of them stopped since them, so if this situation remains for another week, I will close this question. Thank you for everyone so far.

I have seen this before with both timer, and looped services. Usually the case is that an exception is caught that stops the timer or looping thread, but does not restart it as part of the exception recovery.

To your other points...I dont think that there is anything "elegant" about the timer. For me its more straight forward to see a looping operation in code than timer methods. But Elegance is subjective.

Like many respondents have pointed out exceptions are swallowed by timer. In my windows services I use System.Threading.Timer. It has Change(...) method which allows you to start/stop that timer. Possible place for exception could be reentrancy problem - in case when tickTack_Elapsed executes longer than timer period. Usually I write timer loop like this:

The following example implements a simple interval timer, which sets off an alarm every five seconds. When the alarm occurs, a MessageBox displays a count of the number of times the alarm has started and prompts the user as to whether the timer should continue to run.

A Timer is used to raise an event at user-defined intervals. This Windows timer is designed for a single-threaded environment where UI threads are used to perform processing. It requires that the user code have a UI message pump available and always operate from the same thread, or marshal the call onto another thread.

When you use this timer, use the Tick event to perform a polling operation or to display a splash screen for a specified period of time. Whenever the Enabled property is set to true and the Interval property is greater than zero, the Tick event is raised at intervals based on the Interval property setting.

The Windows Forms Timer component is single-threaded, and is limited to an accuracy of 55 milliseconds. If you require a multithreaded timer with greater accuracy, use the Timer class in the System.Timers namespace.

After way too many hours searching for an answer to this, I discovered a wide variety of articles and blogs discussing timers in Windows services. I've seen a lot of opinions on this and they all fall into three categories and in descending order of frequency:

Apparently, System.Timers.Timer hides any exceptions, swallows them quietly, and then chokes. Of course, you can handle these in your method that you've added as a handler to your timer, but if the exception is thrown immediately on entrance (before the first line of code is executed, which can happen if your method declares a variable that uses an object in a strong-named DLL of which you have the wrong version, for instance), you are never going to see that exception.

To add to what "user1820848" wrote, because that was my problem as well, if your System.timers.timer elapsed event doesn't seem to be firing, put everything in the event handler in a try/catch block, and look for any problem there. I tried all of the recommended methods to deal with this problem (or thought I had), including switching from system.timers.timer to system.threading.timer, and that didn't work either.

I had a situation where I have three running services on this server, running essentially the same timer code. I even went line by line with another running service's code to make sure I was doing the system.timers.timer handling the same. But the other service works fine, and this one didn't seem to be firing the event at all.

[Edit: another thing to try is take your code out of the timer event, put it into another sub/function, call that from your startup code, and also put the function call in your timer event. Weeks later, back at my workstation, trying to run the same code, and I have that sinking feeling that my timer event isn't getting called, and I've been here before. Indeed! But putting everything in a try/catch isn't working either!?! Moved it to a function call and Bam, there's my exception - Oracle again. But it wasn't coming up even with every single line inside a try/catch, until I moved the code out of the timer event and tried again.]

A handle to the window to be associated with the timer. This window must be owned by the calling thread. If a NULL value for hWnd is passed in along with an nIDEvent of an existing timer, that timer will be replaced in the same way that an existing non-NULL hWnd timer will be.

A nonzero timer identifier. If the hWnd parameter is NULL, and the nIDEvent does not match an existing timer then it is ignored and a new timer ID is generated. If the hWnd parameter is not NULL and the window specified by hWnd already has a timer with the value nIDEvent, then the existing timer is replaced by the new timer. When SetTimer replaces a timer, the timer is reset. Therefore, a message will be sent after the current time-out value elapses, but the previously set time-out value is ignored. If the call is not intended to replace an existing timer, nIDEvent should be 0 if the hWnd is NULL.

If the function succeeds and the hWnd parameter is NULL, the return value is an integer identifying the new timer. An application can pass this value to the KillTimer function to destroy the timer.

If the function succeeds and the hWnd parameter is not NULL, then the return value is a nonzero integer. An application can pass the value of the nIDEvent parameter to the KillTimer function to destroy the timer.

An application can process WM_TIMER messages by including a WM_TIMER case statement in the window procedure or by specifying a TimerProc callback function when creating the timer. When you specify a TimerProc callback function, the DispatchMessage calls the callback function instead of calling the window procedure when it processes WM_TIMER with a non-NULL lParam. Therefore, you need to dispatch messages in the calling thread, even when you use TimerProc instead of processing WM_TIMER.

The timer identifier, nIDEvent, is specific to the associated window. Another window can have its own timer which has the same identifier as a timer owned by another window. The timers are distinct. 2351a5e196