Usando o WCT
O código de exemplo a seguir demonstra o uso da API de travessia da cadeia de espera. Ele enumera todos os threads no sistema e imprime a cadeia de espera para cada thread.
Para enumerar todos os threads no sistema, execute o exemplo sem parâmetros. Para enumerar somente os threads de um processo especificado, execute o exemplo e passe o identificador de processo como um parâmetro. O exemplo executa as seguintes etapas:
- Chama a função RegisterWaitChainCOMCallback para registrar as funções de retorno de chamada COM.
- Chama a função OpenThreadWaitChainSession para criar a sessão da cadeia de espera.
- Chama a função AdjustTokenPrivileges para habilitar o privilégio SE_DEBUG_NAME.
- Chama as funções EnumProcesses e CreateToolhelp32Snapshot para enumerar os threads especificados.
- Chama o GetThreadWaitChain para recuperar uma matriz de estruturas WAITCHAIN_NODE_INFO que contêm os nós da cadeia de espera.
- Imprime informações da cadeia de espera.
- Chama a função CloseThreadWaitChainSession para limpar a cadeia de espera.
// Copyright (C) Microsoft. All rights reserved.
/*
* Sample code for the Wait Chain Traversal (WCT) API.
*
* This program enumerates all threads in the system and prints the
* wait chain for each of them. It should be run from an elevated
* command prompt to get results for services.
*
*/
#ifndef UNICODE
#define UNICODE
#endif
#include <windows.h>
#include <wct.h>
#include <psapi.h>
#include <tlhelp32.h>
#include <wchar.h>
#include <stdio.h>
#include <stdlib.h>
#pragma comment(lib, "Psapi.lib")
#pragma comment(lib, "Advapi32.lib")
typedef struct _STR_ARRAY
{
CHAR Desc[32];
} STR_ARRAY;
// Human-readable names for the different synchronization types.
STR_ARRAY STR_OBJECT_TYPE[] =
{
{"CriticalSection"},
{"SendMessage"},
{"Mutex"},
{"Alpc"},
{"Com"},
{"ThreadWait"},
{"ProcWait"},
{"Thread"},
{"ComActivation"},
{"Unknown"},
{"Max"}
};
// Global variable to store the WCT session handle
HWCT g_WctHandle = NULL;
// Global variable to store OLE32.DLL module handle.
HMODULE g_Ole32Hnd = NULL;
//
// Function prototypes
//
void
PrintWaitChain (
__in DWORD ThreadId
);
BOOL
GrantDebugPrivilege ( )
/*++
Routine Description:
Enables the debug privilege (SE_DEBUG_NAME) for this process.
This is necessary if we want to retrieve wait chains for processes
not owned by the current user.
Arguments:
None.
Return Value:
TRUE if this privilege could be enabled; FALSE otherwise.
--*/
{
BOOL fSuccess = FALSE;
HANDLE TokenHandle = NULL;
TOKEN_PRIVILEGES TokenPrivileges;
if (!OpenProcessToken(GetCurrentProcess(),
TOKEN_ADJUST_PRIVILEGES | TOKEN_QUERY,
&TokenHandle))
{
printf("Could not get the process token");
goto Cleanup;
}
TokenPrivileges.PrivilegeCount = 1;
if (!LookupPrivilegeValue(NULL,
SE_DEBUG_NAME,
&TokenPrivileges.Privileges[0].Luid))
{
printf("Couldn't lookup SeDebugPrivilege name");
goto Cleanup;
}
TokenPrivileges.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED;
if (!AdjustTokenPrivileges(TokenHandle,
FALSE,
&TokenPrivileges,
sizeof(TokenPrivileges),
NULL,
NULL))
{
printf("Could not revoke the debug privilege");
goto Cleanup;
}
fSuccess = TRUE;
Cleanup:
if (TokenHandle)
{
CloseHandle(TokenHandle);
}
return fSuccess;
}
BOOL
CheckThreads (
__in DWORD ProcId
)
/*++
Routine Description:
Enumerates all threads (or optionally only threads for one
process) in the system. It the calls the WCT API on each of them.
Arguments:
ProcId--Specifies the process ID to analyze. If '0' all processes
in the system will be checked.
Return Value:
TRUE if processes could be checked; FALSE if a general failure
occurred.
--*/
{
DWORD processes[1024];
DWORD numProcesses;
DWORD i;
// Try to enable the SE_DEBUG_NAME privilege for this process.
// Continue even if this fails--we just won't be able to retrieve
// wait chains for processes not owned by the current user.
if (!GrantDebugPrivilege())
{
printf("Could not enable the debug privilege");
}
// Get a list of all processes currently running.
if (EnumProcesses(processes, sizeof(processes), &numProcesses) == FALSE)
{
printf("Could not enumerate processes");
return FALSE;
}
for (i = 0; i < numProcesses / sizeof(DWORD); i++)
{
HANDLE process;
HANDLE snapshot;
if (processes[i] == GetCurrentProcessId())
{
continue;
}
// If the caller specified a Process ID, check if we have a match.
if (ProcId != 0)
{
if (processes[i] != ProcId)
{
continue;
}
}
// Get a handle to this process.
process = OpenProcess(PROCESS_ALL_ACCESS, FALSE, processes[i]);
if (process)
{
WCHAR file[MAX_PATH];
printf("Process 0x%x - ", processes[i]);
// Retrieve the executable name and print it.
if (GetProcessImageFileName(process, file, ARRAYSIZE(file)) > 0)
{
PCWSTR filePart = wcsrchr(file, L'\\');
if (filePart)
{
filePart++;
}
else
{
filePart = file;
}
printf("%S", filePart);
}
printf("\n----------------------------------\n");
// Get a snapshot of all threads and look for the ones
// from the relevant process
snapshot = CreateToolhelp32Snapshot(TH32CS_SNAPTHREAD, 0);
if (snapshot != INVALID_HANDLE_VALUE)
{
THREADENTRY32 thread;
thread.dwSize = sizeof(thread);
// Walk the thread list and print each wait chain
if (Thread32First(snapshot, &thread))
{
do
{
if (thread.th32OwnerProcessID == processes[i])
{
// Open a handle to this specific thread
HANDLE threadHandle = OpenThread(THREAD_ALL_ACCESS,
FALSE,
thread.th32ThreadID);
if (threadHandle)
{
// Check whether the thread is still running
DWORD exitCode;
GetExitCodeThread(threadHandle, &exitCode);
if (exitCode == STILL_ACTIVE)
{
// Print the wait chain.
PrintWaitChain(thread.th32ThreadID);
}
CloseHandle(threadHandle);
}
}
} while (Thread32Next(snapshot, &thread));
}
CloseHandle(snapshot);
}
CloseHandle(process);
printf("\n");
}
}
return TRUE;
}
void
PrintWaitChain (
__in DWORD ThreadId
)
/*++
Routine Description:
Enumerates all threads (or optionally only threads for one
process) in the system. It the calls the WCT API on each thread.
Arguments:
ThreadId--Specifies the thread ID to analyze.
Return Value:
(none)
--*/
{
WAITCHAIN_NODE_INFO NodeInfoArray[WCT_MAX_NODE_COUNT];
DWORD Count, i;
BOOL IsCycle;
printf("%d: ", ThreadId);
Count = WCT_MAX_NODE_COUNT;
// Make a synchronous WCT call to retrieve the wait chain.
if (!GetThreadWaitChain(g_WctHandle,
NULL,
WCTP_GETINFO_ALL_FLAGS,
ThreadId,
&Count,
NodeInfoArray,
&IsCycle))
{
printf("Error (0X%x)\n", GetLastError());
return;
}
// Check if the wait chain is too big for the array we passed in.
if (Count > WCT_MAX_NODE_COUNT)
{
printf("Found additional nodes %d\n", Count);
Count = WCT_MAX_NODE_COUNT;
}
// Loop over all the nodes returned and print useful information.
for (i = 0; i < Count; i++)
{
switch (NodeInfoArray[i].ObjectType)
{
case WctThreadType:
// A thread node contains process and thread ID.
printf("[%x:%x:%s]->",
NodeInfoArray[i].ThreadObject.ProcessId,
NodeInfoArray[i].ThreadObject.ThreadId,
((NodeInfoArray[i].ObjectStatus == WctStatusBlocked) ? "b" : "r"));
break;
default:
// A synchronization object.
// Some objects have names...
if (NodeInfoArray[i].LockObject.ObjectName[0] != L'\0')
{
printf("[%s:%S]->",
STR_OBJECT_TYPE[NodeInfoArray[i].ObjectType-1].Desc,
NodeInfoArray[i].LockObject.ObjectName);
}
else
{
printf("[%s]->",
STR_OBJECT_TYPE[NodeInfoArray[i].ObjectType-1].Desc);
}
if (NodeInfoArray[i].ObjectStatus == WctStatusAbandoned)
{
printf("<abandoned>");
}
break;
}
}
printf("[End]");
// Did we find a deadlock?
if (IsCycle)
{
printf(" !!!Deadlock!!!");
}
printf("\n");
}
void
Usage ()
/*++
Routine Description:
Print usage information to stdout.
--*/
{
printf("\nPrints the thread wait chains for one or all processes in the system.\n\n");
printf("\nUsage:\tWctEnum [ProcId]\n");
printf("\t (no params) -- get the wait chains for all processes\n");
printf("\t ProcId -- get the wait chains for the specified process\n\n");
}
BOOL
InitCOMAccess ()
/*++
Routine Description:
Register COM interfaces with WCT. This enables WCT to provide wait
information if a thread is blocked on a COM call.
--*/
{
PCOGETCALLSTATE CallStateCallback;
PCOGETACTIVATIONSTATE ActivationStateCallback;
// Get a handle to OLE32.DLL. You must keep this handle around
// for the life time for any WCT session.
g_Ole32Hnd = LoadLibrary(L"ole32.dll");
if (!g_Ole32Hnd)
{
printf("ERROR: GetModuleHandle failed: 0x%X\n", GetLastError());
return FALSE;
}
// Retrieve the function addresses for the COM helper APIs.
CallStateCallback = (PCOGETCALLSTATE)
GetProcAddress(g_Ole32Hnd, "CoGetCallState");
if (!CallStateCallback)
{
printf("ERROR: GetProcAddress failed: 0x%X\n", GetLastError());
return FALSE;
}
ActivationStateCallback = (PCOGETACTIVATIONSTATE)
GetProcAddress(g_Ole32Hnd, "CoGetActivationState");
if (!ActivationStateCallback)
{
printf("ERROR: GetProcAddress failed: 0x%X\n", GetLastError());
return FALSE;
}
// Register these functions with WCT.
RegisterWaitChainCOMCallback(CallStateCallback,
ActivationStateCallback);
return TRUE;
}
int _cdecl
wmain (
__in int argc,
__in_ecount(argc) PWSTR* argv
)
/*++
Routine Description:
Main entry point for this application.
--*/
{
int rc = 1;
// Initialize the WCT interface to COM. Continue if this
// fails--there just will not be COM information.
if (!InitCOMAccess())
{
printf("Could not enable COM access\n");
}
// Open a synchronous WCT session.
g_WctHandle = OpenThreadWaitChainSession(0, NULL);
if (NULL == g_WctHandle)
{
printf("ERROR: OpenThreadWaitChainSession failed\n");
goto Cleanup;
}
if (argc < 2)
{
// Enumerate all threads in the system.
CheckThreads(0);
}
else
{
// Only enumerate threads in the specified process.
//
// Take the first command line parameter as the process ID.
DWORD ProcId = 0;
ProcId = _wtoi(argv[1]);
if (ProcId == 0)
{
Usage();
goto Cleanup;
}
CheckThreads(ProcId);
}
// Close the WCT session.
CloseThreadWaitChainSession(g_WctHandle);
rc = 0;
Cleanup:
if (NULL != g_Ole32Hnd)
{
FreeLibrary(g_Ole32Hnd);
}
return rc;
}
Tópicos relacionados
Wait Chain Traversal, WCT Reference, MSDN Magazine 2007 Julho - Bugslayer: Wait Chain Traversal, Suporte da Microsoft: Corrigir problemas com aplicativos da Microsoft Store
Comentários
Em breve: Ao longo de 2024, eliminaremos os problemas do GitHub como o mecanismo de comentários para conteúdo e o substituiremos por um novo sistema de comentários. Para obter mais informações, consulte https://aka.ms/ContentUserFeedback.
Enviar e exibir comentários de