python - 在 Mac OS X 上使用 NLTK 在 Celery 线程中使用 python-javabridge JVM 时出现 fatal error

Question

我正在使用Python wrapper for Weka这是基于 python-javabridge 。我有一项很长的任务要执行，因此，我正在使用 Celery这样做。问题是我明白

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()

据我所知，这可能是由于 JVM 未附加到 Celery 线程所致。但是，javabridge.attach() 确实在其中运行。

我错过了什么？

---

编辑:我确定了导致问​​题的代码。它与 NLTK 有关。分词器。以下代码(根据 Vebjorn's answer )将重现该错误:

# 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，代码可以正常运行。当不作为 Celery 任务运行时它也可以工作。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)中运行，但不能在Mac OS X Yosemite(v10.3)上运行。

---

编辑3:正如评论中提到的，如果from nltk.tokenize import RegexpTokenizer在任务包装器内完成，即在hello内，它就可以工作() 函数。

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)

1. 在原始 Ubuntu 14.04 机器上安装:

   $ 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
   

2. 启动工作线程:

   $ 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.
   

3. 在另一个窗口中，运行客户端五次:

    $ 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!
   

4. 在工作窗口中观察到 JVM 在来自客户端的前四次调用(进入四个不同的进程)时启动，但在第五次调用时未启动:

   [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