test_monkey_patch.py

#
# Demonstrate fdb blocking main thread when the network thread is started.
#

import time

import gevent
import gevent.monkey
gevent.monkey.patch_all() # Works if: (thread=False)

import fdb
fdb.api_version(510)

DB = None

@fdb.transactional
def write_time(tr):
    tr['now'] = bytes(time.time())

@fdb.transactional
def read_time(tr):
    return tr['now']

def get_db():
    global DB
    if DB is not None:
        return DB
    # Doesn't matter whether we use event_model="gevent" or None
    DB = fdb.open(event_model="gevent")
    return DB

def writer():
    while True:
        print 'Writer!'
        write_time(get_db())
        time.sleep(1)

def reader():
    while True:
        print 'Reader!'
        time.sleep(1)
        print read_time(get_db())

gevent.spawn(writer)
gevent.spawn(reader)
gevent.sleep(5)

Expected output:

Writer!
Reader!
Writer!
1524429808.49
Reader!
Writer!
1524429809.5
Reader!
Writer!
1524429810.5
Reader!
Writer!
1524429811.5
Reader!

When network thread blocks main thread, output is:

Writer!
Reader!