Updated process management for Windows.

Author: rashedmyt

matlab_proxy/app.py

@@ -19,7 +19,7 @@
 from matlab_proxy.util import list_servers, mwi
 from matlab_proxy.util.mwi import environment_variables as mwi_env
 from matlab_proxy.util.mwi import token_auth
-from matlab_proxy.util.mwi.exceptions import LicensingError, InvalidTokenError
+from matlab_proxy.util.mwi.exceptions import AppError, LicensingError, InvalidTokenError
 
 mimetypes.add_type("font/woff", ".woff")
 mimetypes.add_type("font/woff2", ".woff2")
@@ -76,11 +76,14 @@ def marshal_error(error):
     """
     if error is None:
         return None
-    return {
-        "message": error.message,
-        "logs": error.logs,
-        "type": error.__class__.__name__,
-    }
+    if isinstance(error, AppError):
+        return {
+            "message": error.message,
+            "logs": error.logs,
+            "type": error.__class__.__name__,
+        }
+    else:
+        return {"message": error.__str__, "logs": "", "type": error.__class__.__name__}
 
 
 async def create_status_response(app, loadUrl=None):

matlab_proxy/util/__init__.py

@@ -11,6 +11,9 @@
 
 logger = mwi.logger.get()
 
+# Global value to detect whether interrupt signal handler has been triggered or not.
+interrupt_signal_caught = False
+
 
 def parse_cli_args():
     """Parses CLI arguments passed to the main() function.
@@ -97,8 +100,18 @@ def catch_interrupt_signal(*args):
         Raises:
             SystemExit: Raises SystemExit which will stop execution of loop.run_forever() in app.main()
         """
-        logger.debug("Interrupt Signal handler called with args:\n", *args)
-        raise SystemExit
+        logger.debug("Interrupt Signal handler called")
+
+        # Only raise SystemExit when the handler is invoked for the first time.
+        # Ignore subsequent handler invocations of interrupt signals. This is
+        # required so that asyncio event loop gracefully cancels pending tasks
+        # and exits.
+        global interrupt_signal_caught
+        if interrupt_signal_caught is False:
+            interrupt_signal_caught = True
+            raise SystemExit
+
+        logger.debug("Interrupt is already being serviced.")
 
     for interrupt_signal in system.get_supported_termination_signals():
         logger.debug(f"Registering handler for signal: {interrupt_signal} ")

matlab_proxy/util/mwi/exceptions.py

@@ -163,7 +163,10 @@ def log_error(logger, err: Exception):
         err (Class): An instance of one of the  Error classes as defined above.
         Example: OnlineLicensingError, EntitlementError
     """
-    logs_str = ("\n" + "\n".join(err.logs)) if err.logs is not None else ""
-    logger.error(
-        err.message if err.message else "An Exception was raised:\n" + logs_str
-    )
+    if isinstance(err, AppError):
+        logs_str = ("\n" + "\n".join(err.logs)) if err.logs is not None else ""
+        logger.error(
+            err.message if err.message else "An Exception was raised:\n" + logs_str
+        )
+    else:
+        logger.error(err)

matlab_proxy/util/windows.py

@@ -5,6 +5,7 @@
 from matlab_proxy.util import mwi
 from matlab_proxy.util.mwi import environment_variables as mwi_env
 
+
 """ This file contains methods specific to non-posix / windows OS.
 """
 
@@ -43,6 +44,7 @@ async def start_matlab(matlab_cmd, matlab_env):
     Returns:
         psutil.Process(): The MATLAB process object.
     """
+    import psutil
 
     intermediate_proc = await asyncio.create_subprocess_exec(
         *matlab_cmd,
@@ -54,12 +56,12 @@ async def start_matlab(matlab_cmd, matlab_env):
     # So, there is no need to check for an intermediate process when testing and can return
     # the same process as a psutil.Process() object.
     if mwi_env.is_testing_mode_enabled() or mwi_env.is_development_mode_enabled():
-        import psutil
-
         proc = psutil.Process(intermediate_proc.pid)
 
         return proc
 
+    matlab = None
+
     try:
         children = util.get_child_processes(intermediate_proc)
 
@@ -76,6 +78,21 @@ async def start_matlab(matlab_cmd, matlab_env):
 
     except AssertionError as err:
         raise err
+    except psutil.NoSuchProcess:
+        # We reach here when the intermediate process launched by matlab-proxy died
+        # before we can query for its child processes. Hence, to find the actual MATLAB
+        # process, we check all the processes name and parent process id. Ideally, this
+        # approach should work in all cases unless MATLAB itself has exited / crashed.
+        logger.debug("Intermediate process not found. Querying all process to find MATLAB")
+        for process in psutil.process_iter():
+            if (
+                process.name() == "MATLAB.exe"
+                and process.ppid() == intermediate_proc.pid
+            ):
+                matlab = process
+                break
+
+    assert matlab != None, "MATLAB Process ID not found"
 
     # Return the actual MATLAB processes
-    return children[0]
+    return matlab