PY-24668 Fix debugging of Python subprocesses called with "-c" parameter

python/helpers/pydev/_pydev_bundle/pydev_monkey.py

@@ -45,8 +45,13 @@ def _get_host_port():
 
 
 def _is_managed_arg(arg):
-    if arg.endswith('pydevd.py'):
-        return True
+    return arg.endswith('pydevd.py')
+
+
+def _is_already_patched(args):
+    for arg in args:
+        if 'pydevd' in arg:
+            return True
     return False
 
 
@@ -138,6 +143,9 @@ def patch_args(args):
             ind_c = get_c_option_index(args)
 
             if ind_c != -1:
+                if _is_already_patched(args):
+                    return args
+
                 host, port = _get_host_port()
 
                 if port is not None:

python/helpers/pydev/pydevd.py

@@ -1478,15 +1478,19 @@ class DispatchReader(ReaderThread):
             self.killReceived = True
 
 
-DISPATCH_APPROACH_NEW_CONNECTION = 1 # Used by PyDev
-DISPATCH_APPROACH_EXISTING_CONNECTION = 2 # Used by PyCharm
-DISPATCH_APPROACH = DISPATCH_APPROACH_NEW_CONNECTION
+def _should_use_existing_connection(setup):
+    '''
+    The new connection dispatch approach is used by PyDev when the `multiprocess` option is set,
+    the existing connection approach is used by PyCharm when the `multiproc` option is set.
+    '''
+    return setup.get('multiproc', False)
+
 
 def dispatch():
     setup = SetupHolder.setup
     host = setup['client']
     port = setup['port']
-    if DISPATCH_APPROACH == DISPATCH_APPROACH_EXISTING_CONNECTION:
+    if _should_use_existing_connection(setup):
         dispatcher = Dispatcher()
         try:
             dispatcher.connect(host, port)
@@ -1616,8 +1620,6 @@ def main():
 
         elif setup['multiproc']: # PyCharm
             pydev_log.debug("Started in multiproc mode\n")
-            global DISPATCH_APPROACH
-            DISPATCH_APPROACH = DISPATCH_APPROACH_EXISTING_CONNECTION
 
             dispatcher = Dispatcher()
             try:

python/testData/debug/test_python_subprocess_another_helper.py

@@ -0,0 +1,5 @@
+def boo():
+    x = 42
+    print("Hello!")
+
+boo()

python/testData/debug/test_python_subprocess_helper.py

@@ -0,0 +1,10 @@
+import subprocess
+import sys
+
+
+def foo():
+    subprocess.call([sys.executable, '-c', "from test_python_subprocess_another_helper import boo"],
+                    stderr=subprocess.PIPE)
+    return 42
+
+foo()

python/testData/debug/test_python_subprocess_with_c_parameter.py

@@ -0,0 +1,6 @@
+from __future__ import print_function
+import subprocess
+import sys
+
+ret = subprocess.call([sys.executable, '-c', "from test_python_subprocess_helper import foo"], stderr=subprocess.PIPE)
+print('The subprocess return code is %d' % ret)

python/testSrc/com/jetbrains/env/python/PythonDebuggerTest.java

@@ -827,6 +827,35 @@ public class PythonDebuggerTest extends PyEnvTestCase {
     });
   }
 
+  @Test
+  public void testPythonSubprocessWithCParameter() {
+    runPythonTest(new PyDebuggerTask("/debug", "test_python_subprocess_with_c_parameter.py") {
+      @Override
+      protected void init() {
+        setMultiprocessDebug(true);
+      }
+
+      @Override
+      public void before() {
+        toggleBreakpoint(getFilePath("test_python_subprocess_another_helper.py"), 2);
+      }
+
+      @Override
+      public void testing() throws Exception {
+        waitForPause();
+        eval("x").hasValue("42");
+        resume();
+        waitForOutput("Hello!");
+      }
+
+      @NotNull
+      @Override
+      public Set<String> getTags() {
+        return ImmutableSet.of("-iron", "-jython");
+      }
+    });
+  }
+
   @Test
   public void testPyQtQThreadInheritor() {
     Assume.assumeFalse("Don't run under Windows",UsefulTestCase.IS_UNDER_TEAMCITY && SystemInfo.isWindows);