Server Timeout Problem

[Miguel Pando]

Hello everyone

Server shells(Createprocess) an application program the first
time a request is received. Server is configured to TerminateProcess
the application, if no new requests are received for, say 6 minutes.

The problem is that the application program is unable to close the
resources used, because of TerminateProcess.

This is the case of a WebServer shelling a FastCGI app.

If the application could detect inactivity for a period of 5 minutes,
then it could close all resources, and shutdown. Thus preempting the server.
Like a yellow light before a red traffic light.

Is this a good approach?

Thank you all.

[Michael Mattias]

> Server is configured to TerminateProcess
> the application, if no new requests are received for, say 6 minutes.

If this is your server, have that terminate itself, don't "terminate process" from either within or without.

If it's not your server, don't "Terminate Process" from yourprogram.. see if you can find a "shutdown" or "exit" command. Or just let it run... it's a SERVER, right?

As per SDK doc:

The TerminateProcess function is used to unconditionally cause a process to exit. Use it only in extreme circumstances. The state of global data maintained by dynamic-link libraries (DLLs) may be compromised if TerminateProcess is used rather than ExitProcess.

MCM

[Michael Mattias]

You need something in your program to know when there's been six minutes inactivity?

Waitable Timer Object Demo June 2005

MCM

[Mike Doty]

See if size of logfile has changed every 5-minutes

#COMPILE EXE
#DIM ALL
#INCLUDE "win32api.inc"
$Logfile = "C:\Abyss Web Server\log\access.log"
FUNCTION PBMAIN () AS LONG
  LOCAL hThread AS DWORD
  THREAD CREATE CheckFileSize(5000) TO hThread   ' (5 minutes  = 300,0000 milliseconds
  THREAD CLOSE hThread TO hThread   
  SLEEP 50
 
  DO 'program loop
    IF THREADCOUNT = 1 THEN EXIT DO
    SLEEP 1000
  LOOP
  ? "Shutdown":SLEEP 1000
END FUNCTION
THREAD FUNCTION CheckFileSize(BYVAL milliseconds AS DWORD) AS LONG
  LOCAL StartSize AS QUAD
  DO
    StartSize = FileSize($LogFile)
    SLEEP milliseconds                       'specified wait
  LOOP UNTIL StartSize = FileSize($LogFile)  'no change, exit
END FUNCTION
FUNCTION FileSize(BYVAL sFileName AS STRING) AS QUAD
  'Bytes = FileSize(sFileName)  returns file size or -1 if any error
  LOCAL FindData AS WIN32_FIND_DATA
  LOCAL hDir AS LONG
  hDir = FindFirstFile(BYVAL STRPTR(sFileName), FindData)
  IF hDir = -1 THEN  'if not found return -1
    FUNCTION = -1
  ELSE               'return number of bytes
    FindClose hDir
    'Thank you, Pierre Bellisle
    FUNCTION = MAK(QUAD, FindData.nFileSizeLow , FindData.nFileSizeHigh)
  END IF
END FUNCTION

[Miguel Pando]

It is not my Server. It is a WebServer(ABYSS) spawning a FastCGI app.

I appreciate your responses, but I'm thinking of a simpler method.

Global Actflag As Long, Actcounter As Long
Function accept_loop()
    DO
        ret=FCGX_Accept_r(cq(n))
        IF ret<0 THEN EXIT DO
        Actflag=1                        'There is activity
        ''''''''
        '''''''
    LOOP
End Function
 
CALLBACK FUNCTION xDialog()
    SELECT CASE CBMSG
        CASE WM_TIMER                'Every 1 minute
                iF Actflag Then
                        Actflag=0 : Actcounter=0
                        Exit Function
                Else
                    If Actcounter=5 then        '5 Minutes
                        FCGX_ShutDownpending    'Preempt the Server TerminateProcess
                        CloseAllResources
                        QuitFlag=1
                        Exit Function
                    Else
                        INCR Actcounter
                    End If
                End If
        CASE ELSE
    END SELECT
END FUNCTION

I get to CloseAllResources before the 6 minutes Server Timeout.

Is this right?

Thanks again

[Michael Mattias]

If it works, it's right.

However, I wouldn't bother with all that counting minutes and looping and stuff.

As long as you have a GUI (CODE NOT SHOWN)...
On WM_CREATE/WM_INITDIALOG
- Create six minute timer
On WM_TIMER
- you hit six minutes, do whatever
On Activity
- Kill the existing timer and create a new one to fire in six minutes.

Looks simpler to me than all those DO loops and global and static variables.

MCM

[Miguel Pando]

>>Looks simpler to me than all those DO loops and global and static variables.

Suppose your timer starts and 2 minutes later there is a request(activity)
then the timer ends, see activity and restarts again.

Two minutes after the timer restarts the WebServer detects no activity for
six minutes, and then TerminateProcess my FastCGI app.

This is what we are trying to avoid.

Am I right?

Thanks

[Mike Doty]

I still like using the Abyss access.log.
With a few more lines of code you can monitor all activity in real-time.

[Michael Mattias]

The problem is that the application program is unable to close the
resources used, because of TerminateProcess.

I 'assume' the code you show (post 5) is what you are running, the process which gets terminated via TerminateProcess() if the server detects no activity from it for six minutes.

Well, there are two obvious solutions:

1. Make sure there is some request - however innocuous - not less than every six minutes.
2. (the CORRECT fix) Don't allow your program to just sit there in a loop holding the resources. Get 'em, use 'em, release 'em before going back into an idle state.


MCM

[Miguel Pando]

I 'assume' the code you show (post 5) is what you are running, the process which gets
terminated via TerminateProcess() if the server detects no activity from it for six minutes.

2. (the CORRECT fix) Don't allow your program to just sit there in a loop holding the
resources. Get 'em, use 'em, release 'em before going back into an idle state.

Actually, the app does not make any request to the Webserver, it is BLOCKED
in the FCGx_Accept_r() function. It unblocks when the server sends a request
coming from a WebBrowser. Then it signals activity by setting the actflag to 1.

If the server does not receive any request from the WebBrowser for the app
in the timeout(6 min) period, it kills the app. The server has its own timeout procedure.


>>See if size of logfile has changed every 5-minutes

I think this has the same problem like the MCM timer procedure.
The solution here seems like we need a higher sampling rate(1 min). When we get 5 samples with no activity then we CloseAllResources, and quit.

Thank you again.

[Michael Mattias]

The solution here seems like we need a higher sampling rate(1 min). When we get 5 samples with no activity then we CloseAllResources

Where's the <expletive> smiley for "kludge" when you need it?

[Miguel Pando]

Excuse me for extending this topic.

But you see, someone offers a "solution" to this problem.
Read all about it here.

Talk about a kludge. I tried their solution, but could not get it to work.
I asked if anyone had any success with it. Seems like no one.

Then I decided to roll my own, and it works!
What could be simpler than this

    SELECT CASE CBMSG
        CASE %WM_TIMER   'Every one minute
                IF actflag THEN
                        actflag=0 : actcount=0
                ELSE
                    IF actcount = 4 THEN
                        quitflag=-1 : FCGX_ShutdownPending
                    ELSE
                        INCR actcount
                    END IF
                END IF

Is this a kludge?

Bye