C - Making a Process Start wait until the process has start-up

Question

I need to make sure that a process is running before moving on with a method   The statement is   Process Start  popup exe      Can you do a WAIT command or set a delay on this value

User · Answer

First of all  I know this is rather old but there still is not an accepted answer  so perhaps my approach will help someone else       What I did to solve this is    process Start     while  true        try               var time   process StartTime          break            catch  Exception         The association var time   process StartTime will throw an exception as long as process did not start  So once it passes  it is safe to assume process is running and to work with it further  I am using this to wait for java process to start up  since it takes some time  This way it should be independent on what machine the application is running rather than using Thread Sleep     I understand this is not very clean solution  but the only one that should be performance independent I could think of

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I used the EventWaitHandle class  On the parent process  create a named EventWaitHandle with initial state of the event set to non-signaled  The parent process blocks until the child process calls the Set method  changing the state of the event to signaled  as shown below   Parent Process   using System  using System Threading  using System Diagnostics   namespace MyParentProcess       class Program               static void Main string   args                        EventWaitHandle ewh   null              try                               ewh   new EventWaitHandle false  EventResetMode AutoReset   CHILD PROCESS READY                     Process process   Process Start  MyChildProcess exe   Process GetCurrentProcess   Id ToString                     if  process    null                                        if  ewh WaitOne 10000                                                    Child process is ready                                                                    catch Exception exception                              finally                               if  ewh    null                      ewh Close                                      Child Process   using System  using System Threading  using System Diagnostics   namespace MyChildProcess       class Program               static void Main string   args                        try                                  Representing some time consuming work                  Thread Sleep 5000                    EventWaitHandle OpenExisting  CHILD PROCESS READY                        Set                     Process GetProcessById Convert ToInt32 args 0                         WaitForExit                              catch  Exception exception

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I also needed this once  and I did a check on the window title of the  process  If it is the one you expect  you can be sure the application is running  The application I was checking needed some time for startup and this method worked fine for me   var process   Process Start  popup exe    while process MainWindowTitle     Title         Thread Sleep 10

User · Answer

I agree with Tom   In addition  to check the processes while performing Thread Sleep  check the running processes  Something like   bool found   0  while   found        foreach  Process clsProcess in Process GetProcesses            if  clsProcess Name    Name              found   true       Thread CurrentThread Sleep 1000

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You can also check if the started process is responsive or not by trying something like this  while process responding

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Are you sure the Start method returns before the child process starts  I was always under the impression that Start starts the child process synchronously   If you want to wait until your child process finishes some sort of initialization then you need inter-process communication - see Interprocess communication for Windows in C    NET 2 0

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Like others have already said  it s not immediately obvious what you re asking   I m going to assume that you want to start a process and then perform another action when the process  is ready      Of course  the  is ready  is the tricky bit   Depending on what you re needs are  you may find that simply waiting is sufficient   However  if you need a more robust solution  you can consider using a named Mutex to control the control flow between your two processes   For example  in your main process  you might create a named mutex and start a thread or task which will wait   Then  you can start the 2nd process   When that process decides that  it is ready   it can open the named mutex  you have to use the same name  of course  and signal to the first process

User · Answer

Do you mean wait until it s done  Then use Process WaitForExit   var process   new Process       StartInfo   new ProcessStartInfo           FileName    popup exe           process Start    process WaitForExit      Alternatively  if it s an application with a UI that you are waiting to enter into a message loop  you can say   process Start    process WaitForInputIdle      Lastly  if neither of these apply  just Thread Sleep for some reasonable amount of time   process Start    Thread Sleep 1000      sleep for one second

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The answer of  ChrisG  is correct  but we need to refresh MainWindowTitle every time and it s better to check for empty     like this   var proc   Process Start  popup exe    while  string IsNullOrEmpty proc MainWindowTitle         System Threading Thread Sleep 100       proc Refresh

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public static class WinApi         DllImport  user32 dll        public static extern bool ShowWindow IntPtr hWnd  int nCmdShow        public static class Windows               public const int NORMAL   1          public const int HIDE   0          public const int RESTORE   9          public const int SHOW   5          public const int MAXIMIXED   3             App  String process name    notepad  Process process  process   Process Start  process name     while   WinApi ShowWindow process MainWindowHandle  WinApi Windows NORMAL         Thread Sleep 100       process Refresh          Done     Continue your code here

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Here an implementation that uses a System Threading Timer  Maybe a bit much for its purpose       private static bool StartProcess string filePath  string processName                if   File Exists filePath               throw new InvalidOperationException   Unknown filepath    string IsNullOrEmpty filePath     EMPTY PATH    filePath               var isRunning   false           using  var resetEvent   new ManualResetEvent false                          void Callback object state                                if   IsProcessActive processName   return                  isRunning   true                     ReSharper disable once AccessToDisposedClosure                 resetEvent Set                               using  new Timer Callback  null  0  TimeSpan FromSeconds 0 5  Milliseconds                                 Process Start filePath                   WaitHandle WaitAny new WaitHandle     resetEvent    TimeSpan FromSeconds 9                                     return isRunning             private static bool StopProcess string processName                if   IsProcessActive processName   return true           var isRunning   true           using  var resetEvent   new ManualResetEvent false                          void Callback object state                                if  IsProcessActive processName   return                  isRunning   false                     ReSharper disable once AccessToDisposedClosure                 resetEvent Set                               using  new Timer Callback  null  0  TimeSpan FromSeconds 0 5  Milliseconds                                 foreach  var process in Process GetProcessesByName processName                       process Kill                    WaitHandle WaitAny new WaitHandle     resetEvent    TimeSpan FromSeconds 9                                     return isRunning             private static bool IsProcessActive string processName                return Process GetProcessesByName processName  Any

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To extend   ChrisG s idea  a little  consider using process MainWindowHandle and seeing if the window message loop is responding   Use p invoke this Win32 api  SendMessageTimeout  From that link      If the function succeeds  the return   value is nonzero  SendMessageTimeout   does not provide information about   individual windows timing out if   HWND BROADCAST is used       If the function fails or times out  the return value is 0  To get   extended error information  call   GetLastError  If GetLastError returns   ERROR TIMEOUT  then the function timed   out

[c#] C# - Making a Process.Start wait until the process has start-up

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