在 Mac OS X 上使用 NLTK 在 Celery 线程中使用 python-javabridge JVM 的致命错误

Question

我正在使用 Python wrapper for Weka which is based on python-javabridge. I have a long task to perform and, therefore, I am using Celery 这样做。问题是我得到

A fatal error has been detected by the Java Runtime Environment:

  SIGSEGV (0xb) at pc=0x00007fff91a3c16f, pid=11698, tid=3587

JRE version:  (8.0_31-b13) (build )
Java VM: Java HotSpot(TM) 64-Bit Server VM (25.31-b07 mixed mode bsd-amd64 compressed oops)
Problematic frame:
C  [libdispatch.dylib+0x616f]  _dispatch_async_f_slow+0x18b

Failed to write core dump. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again

If you would like to submit a bug report, please visit:
    http://bugreport.java.com/bugreport/crash.jsp
The crash happened outside the Java Virtual Machine in native code.
See problematic frame for where to report the bug.

在线程内启动 JVM 时。为此使用了这两行代码（来自weka.core.jvm）：

javabridge.start_vm(run_headless=True)
javabridge.attach()

据我了解，这可能是由于 JVM 未附加到 Celery 线程。但是，javabridge.attach()里面确实是运行。

我错过了什么？

编辑： 我确定了导致问题的代码。它与 NLTK tokenizer. The following code (according to ) 有关，将重现错误：

# hello.py
from nltk.tokenize import RegexpTokenizer
import javabridge
from celery import Celery

app = Celery('hello', broker='amqp://guest@localhost//', backend='amqp')

started = False    

@app.task
def hello():
    global started
    if not started:
        print 'Starting the VM'
        javabridge.start_vm(run_headless=True)
        started = True

    sentence = "This is a sentence with some numbers like 1, 2 or and some weird symbols like @, $ or ! :)"
    tokenizer = RegexpTokenizer(r'\w+')
    tokenized_sentence = tokenizer.tokenize(sentence.lower())
    print "Tokens:", tokenized_sentence

    return javabridge.run_script('java.lang.String.format("Hello, %s!", greetee);',
                             dict(greetee='world'))

在不启动 JVM 的情况下，代码运行正确。它也适用于 not 运行ning 作为 Celery 任务。我不明白为什么它会崩溃。

编辑 2： 它实际上可以在干净的 Ubuntu 环境（Dockerized）中工作，但不能在 Mac OS 中工作X Yosemite (v10.3)。

编辑 3： 如评论中所述，如果 from nltk.tokenize import RegexpTokenizer 在任务包装器内部完成，即在 hello() 函数内部完成，它就会起作用。

Answer 1

默认情况下，Celery 启动四个独立的工作进程。（请参阅 celery worker 的 -c 命令行选项。）您需要确保在所有这些中启动 JVM。这个例子对我有用：

# hello.py
import os
import threading
from celery import Celery
import javabridge

app = Celery('hello', broker='amqp://guest@localhost//', backend='amqp')

started = False

@app.task
def hello():
    global started
    if not started:
        print 'Starting the VM'
        javabridge.start_vm(run_headless=True)
        started = True
    return javabridge.run_script('java.lang.String.format("Hello, %s!", greetee);',
                                 dict(greetee='world'))

和

# client.py
from hello import hello

r = hello.delay()
print r.get(timeout=1)

安装在一个处女Ubuntu 14.04 机器上：

$ sudo apt-get update -y
$ sudo apt-get install -y openjdk-7-jdk python-pip python-numpy python-dev rabbitmq-server
$ sudo pip install celery javabridge
$ sudo /etc/init.d/rabbitmq-server start

开始工作：

$ celery -A hello worker
...
 -------------- celery@a7cc1bedc40d v3.1.17 (Cipater)
---- **** ----- 
--- * ***  * -- Linux-3.16.7-tinycore64-x86_64-with-Ubuntu-14.04-trusty
-- * - **** --- 
- ** ---------- [config]
- ** ---------- .> app:         hello:0x7f5464766b50
- ** ---------- .> transport:   amqp://guest:**@localhost:5672//
- ** ---------- .> results:     amqp
- *** --- * --- .> concurrency: 4 (prefork)
-- ******* ---- 
--- ***** ----- [queues]
 -------------- .> celery           exchange=celery(direct) key=celery


[2015-04-21 10:04:31,262: WARNING/MainProcess] celery@a7cc1bedc40d ready.

在另一个window,运行一个客户五次：

 $ python client.py 
 Hello, world!
 $ python client.py 
 Hello, world!
 $ python client.py 
 Hello, world!
 $ python client.py 
 Hello, world!
 $ python client.py 
 Hello, world!

在 worker 中观察 window JVM 在来自客户端的前四次调用（转到四个不同的进程）中启动，但在第五次调用中没有启动：

[2015-04-21 10:05:53,491: WARNING/Worker-1] Starting the VM
[2015-04-21 10:05:55,028: WARNING/Worker-2] Starting the VM
[2015-04-21 10:05:56,411: WARNING/Worker-3] Starting the VM
[2015-04-21 10:05:57,318: WARNING/Worker-4] Starting the VM

在 Mac OS X 上使用 NLTK 在 Celery 线程中使用 python-javabridge JVM 的致命错误

Fatal error using python-javabridge JVM in Celery thread with NLTK on Mac OS X

python

weka

celery

java-bridge-method