Add basic orphan handling for child processes

pyexasol/http_transport.py

@@ -239,7 +239,11 @@ def send_proxy(self):
         sys.stdout.buffer.flush()
 
     def handle_request(self):
-        self.server.handle_request()
+        # Wait for exactly one connection
+        while self.server.total_clients == 0:
+            self.server.handle_request()
+            utils.check_orphaned()
+
         self.server.server_close()
 
 
@@ -249,6 +253,8 @@ class ExaTCPServer(TCPServer):
     Instead of listening for incoming connections it connects to Exasol and uses proxy magic
     It allows to bypass various connectivity problems (e.g. firewall)
     """
+    timeout = 5
+
     def __init__(self, *args, **kwargs):
         self.proxy_host = None
         self.proxy_port = None
@@ -257,6 +263,8 @@ def __init__(self, *args, **kwargs):
         self.compression = kwargs.pop('compression', False)
         self.encryption = kwargs.pop('encryption', False)
 
+        self.total_clients = 0
+
         super().__init__(*args, **kwargs)
 
     def set_pipe(self, pipe):
@@ -293,6 +301,10 @@ class ExaHTTPRequestHandler(BaseHTTPRequestHandler):
 
     def log_message(self, format, *args): pass
 
+    def setup(self):
+        super().setup()
+        self.server.total_clients += 1
+
     def do_PUT(self):
         # Compressed data loop
         if self.server.compression:

pyexasol/script_output.py

@@ -36,6 +36,8 @@
 import subprocess
 import pathlib
 
+from . import utils
+
 
 class ExaScriptOutputProcess(object):
     def __init__(self, host, port, output_dir=None):
@@ -130,6 +132,9 @@ class ExaScriptOutputServer(socketserver.ThreadingMixIn, socketserver.TCPServer)
     def get_output_address(self):
         return f"{socket.getfqdn()}:{self.socket.getsockname()[1]}"
 
+    def service_actions(self):
+        utils.check_orphaned()
+
 
 class ExaScriptOutputHandler(socketserver.StreamRequestHandler):
     def setup(self):

pyexasol/utils.py

@@ -6,6 +6,7 @@
 import tempfile
 import socket
 import ssl
+import os
 
 from . import constant
 
@@ -105,3 +106,15 @@ def generate_adhoc_ssl_context():
         context.load_cert_chain(certfile=cert_file.name, keyfile=key_file.name)
 
         return context
+
+
+def check_orphaned():
+    """
+    Raise exception if current process is "orphaned" (parent process is dead)
+    It is useful to stop PyEXASOL HTTP servers from being stuck in process list when parent process was killed
+
+    Currently it works only for Unix
+    Please let me know if you know a good way to detect orphans on Windows
+    """
+    if os.getppid() == 1:
+        raise RuntimeError("Current process is orphaned, ppid=1")

pyexasol/version.py

@@ -1 +1 @@
-__version__ = '0.3.29'
+__version__ = '0.3.30'