[lldb] Improved lldb-server stability for remote launching

We faced the issue running cross api tests in 8 threads. The executable is installed to the target by the process `lldb-server platform`, but launched by the another process `lldb-server gdbserver`. We got the error ETXTBSY on Linux and ERROR_SHARING_VIOLATION on Windows. It seems the known issue and ProcessLauncherPosixFork.cpp already contains the workaround, but it is not enough. Updated the workaround with the total timeout 5 seconds and added the same workaround to ProcessLauncherWindows.cpp too.

Author: slydiman

lldb/source/Host/posix/ProcessLauncherPosixFork.cpp

@@ -201,7 +201,7 @@ struct ForkLaunchInfo {
   execve(info.argv[0], const_cast<char *const *>(info.argv), info.envp);
 
 #if defined(__linux__)
-  if (errno == ETXTBSY) {
+  for (int i = 0; i < 50; ++i) {
     // On android M and earlier we can get this error because the adb daemon
     // can hold a write handle on the executable even after it has finished
     // uploading it. This state lasts only a short time and happens only when
@@ -210,7 +210,9 @@ struct ForkLaunchInfo {
     // shell" command in the fork() child before it has had a chance to exec.)
     // Since this state should clear up quickly, wait a while and then give it
     // one more go.
-    usleep(50000);
+    if (errno != ETXTBSY)
+      break;
+    usleep(100000);
     execve(info.argv[0], const_cast<char *const *>(info.argv), info.envp);
   }
 #endif

lldb/source/Host/windows/ProcessLauncherWindows.cpp

@@ -113,14 +113,30 @@ ProcessLauncherWindows::LaunchProcess(const ProcessLaunchInfo &launch_info,
   // command line is not empty, its contents may be modified by CreateProcessW.
   WCHAR *pwcommandLine = wcommandLine.empty() ? nullptr : &wcommandLine[0];
 
-  BOOL result = ::CreateProcessW(
+  BOOL result;
+  DWORD last_error = 0;
+  // This is the workaround for the error "The process cannot access the file
+  // because it is being used by another process". Note the executable file is
+  // installed to the target by the process `lldb-server platform`, but launched
+  // by the process `lldb-server gdbserver`. Sometimes system may block the file
+  // for some time after copying.
+  for (int i = 0; i < 50; ++i) {
+    result = ::CreateProcessW(
       wexecutable.c_str(), pwcommandLine, NULL, NULL, TRUE, flags, env_block,
       wworkingDirectory.size() == 0 ? NULL : wworkingDirectory.c_str(),
       &startupinfo, &pi);
+    if (!result) {
+      last_error = ::GetLastError();
+      if (last_error != ERROR_SHARING_VIOLATION)
+        break;
+      ::Sleep(100);
+    } else
+      break;
+  }
 
   if (!result) {
     // Call GetLastError before we make any other system calls.
-    error.SetError(::GetLastError(), eErrorTypeWin32);
+    error.SetError(last_error, eErrorTypeWin32);
     // Note that error 50 ("The request is not supported") will occur if you
     // try debug a 64-bit inferior from a 32-bit LLDB.
   }