My goal is to write a code snippet that lets me have an exclusive access to an object (f.ex a txt file) in concurrent environment. With this in mind I was testing the simple program built on use of two System.Timers timers. Event handlers of both timers share the same lock object (Please see the code below).
The timers start simultaneously with different interval, 3s for timer1 and 1s for timer2. Timer1 supposed to work only for one cycle, during which it's event handler will sleep for 10s and thus keeping the lock.
What's surprised me is that when the lock released, I don't get all stacked in memory timer2 events (only app. every other of them). I thought, while timer1's event handler has the lock, timer2's events are stacking in memory. But that's apparently not true. Why some timer2 events dissappear?
class Program
{
static int counter = 0;
static readonly object locker = new object();
System.Timers.Timer timer1;
System.Timers.Timer timer2;
static void Main(string[] args)
{
Program p = new Program();
p.timer1 = new System.Timers.Timer(3000);
p.timer1.Elapsed += new ElapsedEventHandler(p.Timer1EventHandler);
p.timer1.Start();
p.timer2 = new System.Timers.Timer(1000);
p.timer2.Elapsed += new ElapsedEventHandler(p.Timer2EventHandler);
p.timer2.Start();
ThreadPool.SetMaxThreads(50, 50);
Console.ReadLine();
}
void Timer1EventHandler(object sender, ElapsedEventArgs e)
{
timer1.Stop();
DoThingsForTimer1Event();
}
void DoThingsForTimer1Event()
{
lock (locker)
{
Console.WriteLine(DateTime.Now + " Timer1 event started." + " Current thread number " + Thread.CurrentThread.ManagedThreadId);
Thread.Sleep(10000);
Console.WriteLine(DateTime.Now + " Timer1 event finished. Lock released.");
}
}
void Timer2EventHandler(object sender, ElapsedEventArgs e)
{
counter++;
lock (locker)
{
Console.WriteLine(DateTime.Now + " Timer2 event fired. Current thread number " + Thread.CurrentThread.ManagedThreadId +
" Counter=" + counter);
}
}
}
