From 0c33b4c2111c33b458a9e2731cbbbe016f1ac570 Mon Sep 17 00:00:00 2001
From: Muawia Khan <muawia@bigchaindb.com>
Date: Thu, 26 Jul 2018 14:42:32 +0200
Subject: [PATCH] Problem: Signals do not propagate to child BigchainDB
 processes (#2395).

Solution: Run child processes as daemons to make the signals propagate. Add a short shutdown description to the setup guide.
---
 bigchaindb/start.py                        | 10 +++---
 docs/server/source/simple-network-setup.md | 42 ++++++++++++++++++++++
 2 files changed, 48 insertions(+), 4 deletions(-)

diff --git a/bigchaindb/start.py b/bigchaindb/start.py
index 4bcc8218..e606ac11 100644
--- a/bigchaindb/start.py
+++ b/bigchaindb/start.py
@@ -1,5 +1,4 @@
 import logging
-
 import setproctitle
 
 import bigchaindb
@@ -34,14 +33,14 @@ BANNER = """
 
 def start():
     # Exchange object for event stream api
+    logger.info('Starting BigchainDB')
     exchange = Exchange()
-
     # start the web api
     app_server = server.create_server(
         settings=bigchaindb.config['server'],
         log_config=bigchaindb.config['log'],
         bigchaindb_factory=BigchainDB)
-    p_webapi = Process(name='bigchaindb_webapi', target=app_server.run)
+    p_webapi = Process(name='bigchaindb_webapi', target=app_server.run, daemon=True)
     p_webapi.start()
 
     # start message
@@ -50,16 +49,18 @@ def start():
     # start websocket server
     p_websocket_server = Process(name='bigchaindb_ws',
                                  target=websocket_server.start,
+                                 daemon=True,
                                  args=(exchange.get_subscriber_queue(EventTypes.BLOCK_VALID),))
     p_websocket_server.start()
 
     # connect to tendermint event stream
     p_websocket_client = Process(name='bigchaindb_ws_to_tendermint',
                                  target=event_stream.start,
+                                 daemon=True,
                                  args=(exchange.get_publisher_queue(),))
     p_websocket_client.start()
 
-    p_exchange = Process(name='bigchaindb_exchange', target=exchange.run)
+    p_exchange = Process(name='bigchaindb_exchange', target=exchange.run, daemon=True)
     p_exchange.start()
 
     # We need to import this after spawning the web server
@@ -69,6 +70,7 @@ def start():
 
     setproctitle.setproctitle('bigchaindb')
 
+    # Start the ABCIServer
     app = ABCIServer(app=App())
     app.run()
 
diff --git a/docs/server/source/simple-network-setup.md b/docs/server/source/simple-network-setup.md
index dc13dd43..a52bde17 100644
--- a/docs/server/source/simple-network-setup.md
+++ b/docs/server/source/simple-network-setup.md
@@ -265,6 +265,48 @@ If you want to refresh your node back to a fresh empty state, then your best bet
 - reset Tendermint using `tendermint unsafe_reset_all`
 - delete the directory `$HOME/.tendermint`
 
+## Shutting down BigchainDB
+
+If you want to stop/kill BigchainDB, you can do so by sending `SIGINT`, `SIGQUIT` or `SIGTERM` to the running BigchainDB
+process(es). Depending on how you started BigchainDB i.e. foreground or background. e.g. you started BigchainDB in the background as mentioned above in the guide:
+
+```bash
+$ nohup bigchaindb start 2>&1 > bigchaindb.log &
+
+$ # Check the PID of the main BigchainDB process
+$ ps -ef | grep bigchaindb
+<user>    *<pid> <ppid>   <C> <STIME> <tty>        <time> bigchaindb
+<user>     <pid> <ppid>*  <C> <STIME> <tty>        <time> gunicorn: master [bigchaindb_gunicorn]
+<user>     <pid> <ppid>*  <C> <STIME> <tty>        <time> bigchaindb_ws
+<user>     <pid> <ppid>*  <C> <STIME> <tty>        <time> bigchaindb_ws_to_tendermint
+<user>     <pid> <ppid>*  <C> <STIME> <tty>        <time> bigchaindb_exchange
+<user>     <pid> <ppid>   <C> <STIME> <tty>        <time> gunicorn: worker [bigchaindb_gunicorn]
+<user>     <pid> <ppid>   <C> <STIME> <tty>        <time> gunicorn: worker [bigchaindb_gunicorn]
+<user>     <pid> <ppid>   <C> <STIME> <tty>        <time> gunicorn: worker [bigchaindb_gunicorn]
+<user>     <pid> <ppid>   <C> <STIME> <tty>        <time> gunicorn: worker [bigchaindb_gunicorn]
+<user>     <pid> <ppid>   <C> <STIME> <tty>        <time> gunicorn: worker [bigchaindb_gunicorn]
+...
+
+$ # Send any of the above mentioned signals to the parent/root process(marked with `*` for clarity)
+# Sending SIGINT
+$ kill -2 <bigchaindb_parent_pid>
+
+$ # OR
+
+# Sending SIGTERM
+$ kill -15 <bigchaindb_parent_pid>
+
+$ # OR
+
+# Sending SIGQUIT
+$ kill -3 <bigchaindb_parent_pid>
+
+# If you want to kill all the processes by name yourself
+$ pgrep bigchaindb | xargs kill -9
+```
+
+If you started BigchainDB in the foreground, a `Ctrl + C` or `Ctrl + Z` would shut down BigchainDB.
+
 ## Member: Dynamically Add a New Member to the Network
 
 TBD.