OpenEuphoria

1. Strange memory issues

• Posted by m_sabal Aug 03, 2012
• 1353 views

Has anyone else seen anything like this? I have a program written and running as a Windows service without any problems for about 6 years now on a physical Windows 2000 server. I've bound it with both Eu3.1 and Eu4.0.3 and both run fine. Running the exact same program on a virtual Windows 2003 server starts fine, but after anywhere from 3 to 12 hours, the program crashes with a type-check error. Examining the ex.err file shows that the crash is never in a consistent location. Yesterday's test had a crash in the Get() function called from a value() function as an example. It looked like the parameter to Get was uninitialized. It seems like the O/S is moving memory around and not putting it back correctly when requested. I've disabled DEP on this machine just to rule it out as a cause with no effect. The funny thing is, my Euphoria service is the only thing having problems on this virtual server. There are a number of other services that have been running well for a year with no problem. I don't get it.

3. Re: Strange memory issues

• Posted by coconut Aug 04, 2012
• 1315 views

Just guessing... Maybe a problem of memory locking... if the service allocate memory but use it without locking it, it may be paged out when it try to used it and that generate an exception. If so try these API call. On a VM memory as more chance to be paged out as resources are shared by many VM.

global function GlobalAlloc(atom flags, integer nBytes) 
    return c_func(iGlobalAlloc,{flags,nBytes}) 
end function 
 
global procedure GlobalFree(atom hmem) 
atom ok 
    ok = c_func(iGlobalFree,{hmem}) 
end procedure 
 
global function GlobalLock(atom hGlobalMem) 
    return c_func(iGlobalLock,{hGlobalMem}) 
end function 
 
global procedure GlobalUnlock(atom GlobalPtr) 
   c_proc(iGlobalUnlock,{GlobalPtr}) 
end procedure 
 
global function GlobalSize(atom hGlobal) 
  return c_func(iGlobalSize,{hGlobal}) 
end function 

for more information look at: memory

Jacques

5. Re: Strange memory issues

• Posted by coconut Aug 04, 2012
• 1232 views

It's not about prohibiting memory paging, it's about locking some allocated memory the time needed to access it.

-- how to use allocated memory 
 
atom pointer = GlobalAlloc(100) 
 
atom LockedMemory= GlobalLock(pointer) -- now it can't be paged out. 
 
--peek or poke to LockedMemory 
 
GlobalUnlock(LockedMemory) -- now it can be paged out. 
 

In windows paging is done with 4096 bytes page, so this in fact lock the whole page containing this 100 bytes and only this page.

NOTE There is LocalAlloc(), LocalFree(), LocalLock() and LocalUnlock() too if that memory is private to the application.

Jacques