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[DO NOT MERGE] Implemented thread pool to handle concurrent connections #1

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[DO NOT MERGE] Implemented thread pool to handle concurrent connections #1

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30 changes: 30 additions & 0 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,36 @@ $ python3 tests/benchmarks/performance.py
+--------------+---------------+-----------------------------------------+---------------------------+--------------------+---------------------+
```

### lilcache vs redis

**Note: lilcache was running with connection pool**
High number of threads is performing worse than no threads.
Seems like Python GIL is biting us here.

```
$ python3 tests/benchmarks/performance.py
+--------------+---------------+-----------------------------------------+---------------------------+--------------------+---------------------+
| Cache type | Concurrency | Number of operations (get/set/delete) | Mean response time (ms) | Lowest time (ms) | Highest time (ms) |
+==============+===============+=========================================+===========================+====================+=====================+
| lilcache | 1 | 1000 | 0.0102515 | 0.00786781 | 0.223398 |
+--------------+---------------+-----------------------------------------+---------------------------+--------------------+---------------------+
| redis | 1 | 1000 | 0.0333166 | 0.0283718 | 1.07622 |
+--------------+---------------+-----------------------------------------+---------------------------+--------------------+---------------------+
| lilcache | 5 | 1000 | 0.0693438 | 0.0123978 | 0.691175 |
+--------------+---------------+-----------------------------------------+---------------------------+--------------------+---------------------+
| redis | 5 | 1000 | 0.0532017 | 0.0312328 | 1.34492 |
+--------------+---------------+-----------------------------------------+---------------------------+--------------------+---------------------+
| lilcache | 10 | 1000 | 0.233874 | 0.0140667 | 2.32434 |
+--------------+---------------+-----------------------------------------+---------------------------+--------------------+---------------------+
| redis | 10 | 1000 | 0.0799031 | 0.0324249 | 2.46119 |
+--------------+---------------+-----------------------------------------+---------------------------+--------------------+---------------------+
| lilcache | 20 | 1000 | 0.578124 | 0.0114441 | 8.94666 |
+--------------+---------------+-----------------------------------------+---------------------------+--------------------+---------------------+
| redis | 20 | 1000 | 0.100958 | 0.0321865 | 4.00949 |
+--------------+---------------+-----------------------------------------+---------------------------+--------------------+---------------------+
```


## Timeline

- [ ] Write unittests
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73 changes: 43 additions & 30 deletions lilcache/cache.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@
"""

import os
import threading
import socket
import pickle

Expand All @@ -17,34 +18,11 @@
NONE_VALUE = pickle.dumps(None)
RESPONSE_OK = b"OK"
RESPONSE_ERROR = b"ERR"
cache = dict()


def _handler(conn, cache_path, snapshot, expires):
pass


def is_last(packet):
return packet.endswith(END_LIMIT)


def manager(sock_path, cache_path, snapshot, expires, poolsize):
"""
The manager thread.

poolsize is used to manage the persistent client connections to the
manager. If there are more than desired connections, then we kill
the most infrequently used connections.

TODO: Later think about snapshot and expires!
"""
cache = dict()

mgr = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
mgr.bind(sock_path)
mgr.listen()

def handle_connection(conn, cache_path, snapshot, expires):
while True:
conn, addr = mgr.accept()
command = conn.recv(BUFFER_SIZE)
packet = command
while not is_last(command):
Expand All @@ -62,7 +40,7 @@ def manager(sock_path, cache_path, snapshot, expires, poolsize):
cache[key] = value
except Exception as e:
payload = create_payload(RESPONSE_ERROR, BUFFER_SIZE,
pickle.dumps(e))
pickle.dumps(e))
else:
payload = create_payload(RESPONSE_OK, BUFFER_SIZE)
elif args[0] == b'POP':
Expand All @@ -76,12 +54,47 @@ def manager(sock_path, cache_path, snapshot, expires, poolsize):
conn.send(p)


def is_last(packet):
return packet.endswith(END_LIMIT)



def manager(sock_path, cache_path, snapshot, expires, poolsize):
"""
The manager thread.

poolsize is used to manage the persistent client connections to the
manager. If there are more than desired connections, then we kill
the most infrequently used connections.

TODO: Later think about snapshot and expires!
"""
mgr = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
mgr.bind(sock_path)
mgr.listen()

connection_pool = []

while True:
conn, addr = mgr.accept()
if len(connection_pool) <= poolsize:
# Handle it in a thread
th = threading.Thread(target=handle_connection,
args=(conn, cache_path, snapshot, expires))
th.setDaemon(True)
th.start()
connection_pool.append(th)
continue
else:
raise NotImplemented("poolsize should be equal or more than 'expected' "
"concurrency level")

def init(
cache_name=None,
root=None,
snapshot=None,
expires=None,
poolsize=10
poolsize=20
):
if not cache_name:
cache_name = generate_cache_name()
Expand All @@ -97,13 +110,10 @@ def init(
if os.path.exists(sock_path):
return

import threading
mgr = threading.Thread(target=manager,
args=(sock_path, cache_path, snapshot, expires, poolsize))
mgr.setDaemon(True)
mgr.start()
# manager(sock_path, cache_path, snapshot, expires, poolsize)
return


def establish_connection():
Expand All @@ -112,10 +122,13 @@ def establish_connection():

We should try to reuse connections (from the connection pool)
"""
if "connection" in STATE:
return STATE["connection"]
sock_path = STATE["sock_path"]
if os.path.exists(sock_path):
conn = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
conn.connect(sock_path)
STATE["connection"] = conn
return conn


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