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'CreateToolhelp32Snapshot' - Memory Leak

Hello,

I need to understand whether the code below causes a memory leak or not...

The function 'CreateToolhelp32Snapshot' returns a handle, does the handle get released back to the system when the function ends or do you have to explicitly call 'CloseHandle'…?


Private Sub JobExecRunning()

    Dim l_lSnapShot As Long
   
    l_lSnapShot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0&)
    If (l_lSnapShot <> 0) Then

           'Do some processing
           ‘CloseHandle(l_lSnapShot) is never called…Good or Bad..?

    End If

End Function

Thanks in advance for your help....

Ian Carrick




0
ISC
Asked:
ISC
1 Solution
 
zzzzzoocCommented:
You have to use CloseHandle() because an the snapshot is an object.
0
 
EDDYKTCommented:
zzzzzooc is right. Do not accept as answer.
Here is an example from http://www.allapi.net/


Const TH32CS_SNAPHEAPLIST = &H1
Const TH32CS_SNAPPROCESS = &H2
Const TH32CS_SNAPTHREAD = &H4
Const TH32CS_SNAPMODULE = &H8
Const TH32CS_SNAPALL = (TH32CS_SNAPHEAPLIST Or TH32CS_SNAPPROCESS Or TH32CS_SNAPTHREAD Or TH32CS_SNAPMODULE)
Const TH32CS_INHERIT = &H80000000
Const MAX_PATH As Integer = 260
Private Type PROCESSENTRY32
    dwSize As Long
    cntUsage As Long
    th32ProcessID As Long
    th32DefaultHeapID As Long
    th32ModuleID As Long
    cntThreads As Long
    th32ParentProcessID As Long
    pcPriClassBase As Long
    dwFlags As Long
    szExeFile As String * MAX_PATH
End Type
Private Declare Function CreateToolhelp32Snapshot Lib "Kernel32" (ByVal lFlags As Long, ByVal lProcessID As Long) As Long
Private Declare Function Process32First Lib "Kernel32" (ByVal hSnapShot As Long, uProcess As PROCESSENTRY32) As Long
Private Declare Function Process32Next Lib "Kernel32" (ByVal hSnapShot As Long, uProcess As PROCESSENTRY32) As Long
Private Declare Sub CloseHandle Lib "Kernel32" (ByVal hPass As Long)
Private Sub Form_Load()
    'KPD-Team 2000
    'URL: http://www.allapi.net/
    'E-Mail: KPDTeam@Allapi.net
    Dim hSnapShot As Long, uProcess As PROCESSENTRY32
    'Takes a snapshot of the processes and the heaps, modules, and threads used by the processes
    hSnapShot = CreateToolhelp32Snapshot(TH32CS_SNAPALL, 0&)
    'set the length of our ProcessEntry-type
    uProcess.dwSize = Len(uProcess)
    'Retrieve information about the first process encountered in our system snapshot
    r = Process32First(hSnapShot, uProcess)
    'set graphics mode to persistent
    Me.AutoRedraw = True
    Do While r
        Me.Print Left$(uProcess.szExeFile, IIf(InStr(1, uProcess.szExeFile, Chr$(0)) > 0, InStr(1, uProcess.szExeFile, Chr$(0)) - 1, 0))
        'Retrieve information about the next process recorded in our system snapshot
        r = Process32Next(hSnapShot, uProcess)
    Loop
    'close our snapshot handle
    CloseHandle hSnapShot
End Sub

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