[ 
https://issues.apache.org/jira/browse/SPARK-12717?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Edward Walker updated SPARK-12717:
----------------------------------
    Description: 
The following multi-threaded program that uses broadcast variables consistently 
throws exceptions like:  Exception("Broadcast variable '18' not 
loaded!",) --- even when run with "--master local[10]".

try:                                                                            
                               
    import pyspark                                                              
                               
except:                                                                         
                               
    pass                                                                        
                               
from optparse import OptionParser                                               
                               
                                                                                
                               
def my_option_parser():                                                         
                               
    op = OptionParser()                                                         
                               
    op.add_option("--parallelism", dest="parallelism", type="int", default=2)   
                               
    return op                                                                   
                               
                                                                                
                               
def do_process(x, w):                                                           
                               
    return x * w.value                                                          
                               
                                                                                
                               
def func(name, rdd, conf):                                                      
                               
    new_rdd = rdd.map(lambda x :   do_process(x, conf))                         
                               
    total = new_rdd.reduce(lambda x, y : x + y)                                 
                               
    count = rdd.count()                                                         
                               
    print name, 1.0 * total / count                                             
                               
                                                                                
                               
if __name__ == "__main__":                                                      
                               
    import threading                                                            
                               
    op = my_option_parser()                                                     
                               
    options, args = op.parse_args()                                             
                               
    sc = pyspark.SparkContext(appName="Buggy")                                  
                               
    data_rdd = sc.parallelize(range(0,1000), 1)                                 
                               
    confs = [ sc.broadcast(i) for i in xrange(options.parallelism) ]            
                               
    threads = [ threading.Thread(target=func, args=["thread_" + str(i), 
data_rdd, confs[i]]) for i in xrange(options.parallelism) ]                     
                                                                     
    for t in threads:                                                           
                               
        t.start()                                                               
                               
    for t in threads:                                                           
                               
        t.join() 

Abridged run output:

% spark-submit --master local[10] bug_spark.py --parallelism 20
[snip]
16/01/08 17:10:20 ERROR Executor: Exception in task 0.0 in stage 9.0 (TID 9)
org.apache.spark.api.python.PythonException: Traceback (most recent call last):
  File 
"/Network/Servers/mother.adverplex.com/Volumes/homeland/Users/walker/.spark/spark-1.6.0-bin-hadoop2.6/python/lib/pyspark.zip/pyspark/worker.py",
 line 98, in main
    command = pickleSer._read_with_length(infile)
  File 
"/Network/Servers/mother.adverplex.com/Volumes/homeland/Users/walker/.spark/spark-1.6.0-bin-hadoop2.6/python/lib/pyspark.zip/pyspark/serializers.py",
 line 164, in _read_with_length
    return self.loads(obj)
  File 
"/Network/Servers/mother.adverplex.com/Volumes/homeland/Users/walker/.spark/spark-1.6.0-bin-hadoop2.6/python/lib/pyspark.zip/pyspark/serializers.py",
 line 422, in loads
    return pickle.loads(obj)
  File 
"/Network/Servers/mother.adverplex.com/Volumes/homeland/Users/walker/.spark/spark-1.6.0-bin-hadoop2.6/python/lib/pyspark.zip/pyspark/broadcast.py",
 line 39, in _from_id
    raise Exception("Broadcast variable '%s' not loaded!" % bid)
Exception: (Exception("Broadcast variable '6' not loaded!",), <function 
_from_id at 0xce7a28>, (6L,))

        at 
org.apache.spark.api.python.PythonRunner$$anon$1.read(PythonRDD.scala:166)
        at 
org.apache.spark.api.python.PythonRunner$$anon$1.<init>(PythonRDD.scala:207)
        at org.apache.spark.api.python.PythonRunner.compute(PythonRDD.scala:125)
        at org.apache.spark.api.python.PythonRDD.compute(PythonRDD.scala:70)
        at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:306)
        at org.apache.spark.rdd.RDD.iterator(RDD.scala:270)
        at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:66)
        at org.apache.spark.scheduler.Task.run(Task.scala:89)
        at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:213)
        at 
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at 
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:745)
[snip]


  was:
The following multi-threaded program that uses broadcast variables consistently 
throws exceptions like:  Exception("Broadcast variable '18' not 
loaded!",) --- even when run with "--master local[10]".

<code>
try:                                                                            
                               
    import pyspark                                                              
                               
except:                                                                         
                               
    pass                                                                        
                               
from optparse import OptionParser                                               
                               
                                                                                
                               
def my_option_parser():                                                         
                               
    op = OptionParser()                                                         
                               
    op.add_option("--parallelism", dest="parallelism", type="int", default=2)   
                               
    return op                                                                   
                               
                                                                                
                               
def do_process(x, w):                                                           
                               
    return x * w.value                                                          
                               
                                                                                
                               
def func(name, rdd, conf):                                                      
                               
    new_rdd = rdd.map(lambda x :   do_process(x, conf))                         
                               
    total = new_rdd.reduce(lambda x, y : x + y)                                 
                               
    count = rdd.count()                                                         
                               
    print name, 1.0 * total / count                                             
                               
                                                                                
                               
if __name__ == "__main__":                                                      
                               
    import threading                                                            
                               
    op = my_option_parser()                                                     
                               
    options, args = op.parse_args()                                             
                               
    sc = pyspark.SparkContext(appName="Buggy")                                  
                               
    data_rdd = sc.parallelize(range(0,1000), 1)                                 
                               
    confs = [ sc.broadcast(i) for i in xrange(options.parallelism) ]            
                               
    threads = [ threading.Thread(target=func, args=["thread_" + str(i), 
data_rdd, confs[i]]) for i in xrange(options.parallelism) ]                     
                                                                     
    for t in threads:                                                           
                               
        t.start()                                                               
                               
    for t in threads:                                                           
                               
        t.join() 
</code>

Abridged run output:
```
% spark-submit --master local[10] bug_spark.py --parallelism 20
[snip]
16/01/08 17:10:20 ERROR Executor: Exception in task 0.0 in stage 9.0 (TID 9)
org.apache.spark.api.python.PythonException: Traceback (most recent call last):
  File 
"/Network/Servers/mother.adverplex.com/Volumes/homeland/Users/walker/.spark/spark-1.6.0-bin-hadoop2.6/python/lib/pyspark.zip/pyspark/worker.py",
 line 98, in main
    command = pickleSer._read_with_length(infile)
  File 
"/Network/Servers/mother.adverplex.com/Volumes/homeland/Users/walker/.spark/spark-1.6.0-bin-hadoop2.6/python/lib/pyspark.zip/pyspark/serializers.py",
 line 164, in _read_with_length
    return self.loads(obj)
  File 
"/Network/Servers/mother.adverplex.com/Volumes/homeland/Users/walker/.spark/spark-1.6.0-bin-hadoop2.6/python/lib/pyspark.zip/pyspark/serializers.py",
 line 422, in loads
    return pickle.loads(obj)
  File 
"/Network/Servers/mother.adverplex.com/Volumes/homeland/Users/walker/.spark/spark-1.6.0-bin-hadoop2.6/python/lib/pyspark.zip/pyspark/broadcast.py",
 line 39, in _from_id
    raise Exception("Broadcast variable '%s' not loaded!" % bid)
Exception: (Exception("Broadcast variable '6' not loaded!",), <function 
_from_id at 0xce7a28>, (6L,))

        at 
org.apache.spark.api.python.PythonRunner$$anon$1.read(PythonRDD.scala:166)
        at 
org.apache.spark.api.python.PythonRunner$$anon$1.<init>(PythonRDD.scala:207)
        at org.apache.spark.api.python.PythonRunner.compute(PythonRDD.scala:125)
        at org.apache.spark.api.python.PythonRDD.compute(PythonRDD.scala:70)
        at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:306)
        at org.apache.spark.rdd.RDD.iterator(RDD.scala:270)
        at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:66)
        at org.apache.spark.scheduler.Task.run(Task.scala:89)
        at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:213)
        at 
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
        at 
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
        at java.lang.Thread.run(Thread.java:745)
[snip]
```


> pyspark broadcast fails when using multiple threads
> ---------------------------------------------------
>
>                 Key: SPARK-12717
>                 URL: https://issues.apache.org/jira/browse/SPARK-12717
>             Project: Spark
>          Issue Type: Bug
>          Components: PySpark
>    Affects Versions: 1.6.0
>         Environment: Linux, python 2.6 or python 2.7.
>            Reporter: Edward Walker
>
> The following multi-threaded program that uses broadcast variables 
> consistently throws exceptions like:  Exception("Broadcast variable '18' not 
> loaded!",) --- even when run with "--master local[10]".
> try:                                                                          
>                                  
>     import pyspark                                                            
>                                  
> except:                                                                       
>                                  
>     pass                                                                      
>                                  
> from optparse import OptionParser                                             
>                                  
>                                                                               
>                                  
> def my_option_parser():                                                       
>                                  
>     op = OptionParser()                                                       
>                                  
>     op.add_option("--parallelism", dest="parallelism", type="int", default=2) 
>                                  
>     return op                                                                 
>                                  
>                                                                               
>                                  
> def do_process(x, w):                                                         
>                                  
>     return x * w.value                                                        
>                                  
>                                                                               
>                                  
> def func(name, rdd, conf):                                                    
>                                  
>     new_rdd = rdd.map(lambda x :   do_process(x, conf))                       
>                                  
>     total = new_rdd.reduce(lambda x, y : x + y)                               
>                                  
>     count = rdd.count()                                                       
>                                  
>     print name, 1.0 * total / count                                           
>                                  
>                                                                               
>                                  
> if __name__ == "__main__":                                                    
>                                  
>     import threading                                                          
>                                  
>     op = my_option_parser()                                                   
>                                  
>     options, args = op.parse_args()                                           
>                                  
>     sc = pyspark.SparkContext(appName="Buggy")                                
>                                  
>     data_rdd = sc.parallelize(range(0,1000), 1)                               
>                                  
>     confs = [ sc.broadcast(i) for i in xrange(options.parallelism) ]          
>                                  
>     threads = [ threading.Thread(target=func, args=["thread_" + str(i), 
> data_rdd, confs[i]]) for i in xrange(options.parallelism) ]                   
>                                                                        
>     for t in threads:                                                         
>                                  
>         t.start()                                                             
>                                  
>     for t in threads:                                                         
>                                  
>         t.join() 
> Abridged run output:
> % spark-submit --master local[10] bug_spark.py --parallelism 20
> [snip]
> 16/01/08 17:10:20 ERROR Executor: Exception in task 0.0 in stage 9.0 (TID 9)
> org.apache.spark.api.python.PythonException: Traceback (most recent call 
> last):
>   File 
> "/Network/Servers/mother.adverplex.com/Volumes/homeland/Users/walker/.spark/spark-1.6.0-bin-hadoop2.6/python/lib/pyspark.zip/pyspark/worker.py",
>  line 98, in main
>     command = pickleSer._read_with_length(infile)
>   File 
> "/Network/Servers/mother.adverplex.com/Volumes/homeland/Users/walker/.spark/spark-1.6.0-bin-hadoop2.6/python/lib/pyspark.zip/pyspark/serializers.py",
>  line 164, in _read_with_length
>     return self.loads(obj)
>   File 
> "/Network/Servers/mother.adverplex.com/Volumes/homeland/Users/walker/.spark/spark-1.6.0-bin-hadoop2.6/python/lib/pyspark.zip/pyspark/serializers.py",
>  line 422, in loads
>     return pickle.loads(obj)
>   File 
> "/Network/Servers/mother.adverplex.com/Volumes/homeland/Users/walker/.spark/spark-1.6.0-bin-hadoop2.6/python/lib/pyspark.zip/pyspark/broadcast.py",
>  line 39, in _from_id
>     raise Exception("Broadcast variable '%s' not loaded!" % bid)
> Exception: (Exception("Broadcast variable '6' not loaded!",), <function 
> _from_id at 0xce7a28>, (6L,))
>       at 
> org.apache.spark.api.python.PythonRunner$$anon$1.read(PythonRDD.scala:166)
>       at 
> org.apache.spark.api.python.PythonRunner$$anon$1.<init>(PythonRDD.scala:207)
>       at org.apache.spark.api.python.PythonRunner.compute(PythonRDD.scala:125)
>       at org.apache.spark.api.python.PythonRDD.compute(PythonRDD.scala:70)
>       at org.apache.spark.rdd.RDD.computeOrReadCheckpoint(RDD.scala:306)
>       at org.apache.spark.rdd.RDD.iterator(RDD.scala:270)
>       at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:66)
>       at org.apache.spark.scheduler.Task.run(Task.scala:89)
>       at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:213)
>       at 
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
>       at 
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
>       at java.lang.Thread.run(Thread.java:745)
> [snip]



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