Parallel processing

src/trimage/ThreadPool.py

@@ -0,0 +1,262 @@
+'''
+ThreadPool Implementation
+
+@author: Morten Holdflod Moeller - morten@holdflod.dk
+@license: LGPL v3 
+
+(A buggy line commented out by Kalman Tarnay...
+see: http://code.google.com/p/pythonthreadpool/issues/detail?id=4 )
+'''
+
+from __future__ import with_statement
+from threading import Thread, RLock
+from time import sleep
+from Queue import Queue, Empty
+import logging
+
+class ThreadPoolMixIn:
+    """Mix-in class to handle each request in a new thread from the ThreadPool."""
+
+    def __init__(self, threadpool=None):
+        if (threadpool == None):
+            threadpool = ThreadPool()
+            self.__private_threadpool = True
+        else:
+            self.__private_threadpool = False
+        
+        self.__threadpool = threadpool
+
+    def process_request_thread(self, request, client_address):
+        """Same as in BaseServer but as a thread.
+
+        In addition, exception handling is done here.
+
+        """
+        try:
+            self.finish_request(request, client_address)
+            self.close_request(request)
+        except:
+            self.handle_error(request, client_address) #IGNORE:W0702
+            self.close_request(request)
+
+    def process_request(self, request, client_address):
+        self.__threadpool.add_job(self.process_request_thread, [request, client_address])      
+
+    def shutdown(self):
+        if (self.__private_threadpool): self.__threadpool.shutdown()
+        
+
+class AddJobException(Exception):
+    '''
+    Exceptoion raised when a Job could not be added
+    to the queue
+    '''
+    def __init__(self, msg):
+        Exception.__init__(self, msg)
+    
+
+class ThreadPool:
+    '''
+    The class implementing the ThreadPool.
+    
+    Instantiate and add jobs using add_job(func, args_list) 
+    '''
+
+    class Job: #IGNORE:R0903
+        '''
+        Class encapsulating a job to be handled
+        by ThreadPool workers 
+        '''
+        def __init__(self, function, args, return_callback=None):
+            self.callable = function
+            self.arguments = args
+            self.return_callback = return_callback
+            
+        def execute(self):
+            '''
+            Called to execute the function
+            '''
+            try:
+                return_value = self.callable(*self.arguments) #IGNORE:W0142
+            except Exception, excep: #IGNORE:W0703
+                logger = logging.getLogger("threadpool.worker")
+                logger.warning("A job in the ThreadPool raised an exception: " + excep)
+                #else do nothing cause we don't know what to do...
+                return 
+                    
+            try:
+                if (self.return_callback != None):
+                    self.return_callback(return_value)
+            except Exception, _: #IGNORE:W0703 everything could go wrong... 
+                logger = logging.getLogger('threadpool')
+                logger.warning('Error while delivering return value to callback function')
+
+    class Worker(Thread):
+        '''
+        A worker thread handling jobs in the thread pool 
+        job queue
+        '''
+        
+        def __init__(self, pool):
+            Thread.__init__(self)
+            
+            if (not isinstance(pool, ThreadPool)):
+                raise TypeError("pool is not a ThreadPool instance")
+            
+            self.pool = pool
+            
+            self.alive = True
+            self.start()
+                
+        def run(self):
+            '''
+            The workers main-loop getting jobs from queue 
+            and executing them
+            '''
+            while self.alive:
+                job = self.pool.get_job()
+                if (job != None):
+                    job.execute()
+                else:
+                    self.alive = False
+                
+            self.pool.punch_out()
+                       
+    def __init__(self, max_workers = 5, kill_workers_after = 3):
+        if (not isinstance(max_workers, int)):
+            raise TypeError("max_workers is not an int")
+        if (max_workers < 1):
+            raise ValueError('max_workers must be >= 1')
+        
+        if (not isinstance(kill_workers_after, int)):
+            raise TypeError("kill_workers_after is not an int")
+        
+        self.__max_workers = max_workers
+        self.__kill_workers_after = kill_workers_after
+        
+        # This Queue is assumed Thread Safe
+        self.__jobs = Queue()
+                      
+        self.__active_workers_lock = RLock() 
+        self.__active_workers = 0
+        
+        self.__shutting_down = False
+        logger = logging.getLogger('threadpool')
+        logger.info('started')
+    
+    def shutdown(self,  wait_for_workers_period = 1, clean_shutdown_reties = 5):
+        if (not isinstance(clean_shutdown_reties, int)):
+            raise TypeError("clean_shutdown_reties is not an int")
+        if (not clean_shutdown_reties >= 0):
+            raise ValueError('clean_shutdown_reties must be >= 0')
+        
+        if (not isinstance(wait_for_workers_period, int)):
+            raise TypeError("wait_for_workers_period is not an int")
+        if (not wait_for_workers_period >= 0):
+            raise ValueError('wait_for_workers_period must be >= 0')
+        
+        logger = logging.getLogger("threadpool")
+        logger.info("shutting down")
+        
+        with self.__active_workers_lock:
+            self.__shutting_down = True
+            self.__max_workers = 0
+            self.__kill_workers_after = 0
+        
+        retries_left = clean_shutdown_reties
+        while (retries_left > 0):
+            
+            with self.__active_workers_lock:
+                logger.info("waiting for workers to shut down (%i), %i workers left"%(retries_left, self.__active_workers))
+                if (self.__active_workers > 0):
+                    retries_left -= 1
+                else:
+                    retries_left = 0
+                    
+                sleep(wait_for_workers_period)
+        
+        
+        with self.__active_workers_lock:
+            if (self.__active_workers > 0):
+                logger.warning("shutdown stopped waiting. Still %i active workers"%self.__active_workers)
+                clean_shutdown = False
+            else:
+                clean_shutdown = True
+            
+        logger.info("shutdown complete")
+        
+        return clean_shutdown
+    
+    def punch_out(self):
+        '''
+        Called by worker to update worker count 
+        when the worker is shutting down
+        '''
+        with self.__active_workers_lock:
+            self.__active_workers -= 1
+        
+    def __new_worker(self):
+        '''
+        Adding a new worker thread to the thread pool
+        '''
+        with self.__active_workers_lock:
+            ThreadPool.Worker(self)
+            self.__active_workers += 1
+        
+    def add_job(self, function, args = None, return_callback=None):
+        '''
+        Put new job into queue
+        '''
+        
+        if (not callable(function)):
+            raise TypeError("function is not a callable")
+        if (not ( args == None or isinstance(args, list))):
+            raise TypeError("args is not a list")
+        if (not (return_callback == None or callable(return_callback))):
+            raise TypeError("return_callback is not a callable")
+                
+        if (args == None):
+            args = []
+        
+        job = ThreadPool.Job(function, args, return_callback)
+        
+        with self.__active_workers_lock:
+            if (self.__shutting_down):
+                raise AddJobException("ThreadPool is shutting down")
+
+            try:
+                start_new_worker = False
+                if (self.__active_workers < self.__max_workers):
+                    #DIY fixed.... FIXME
+                    #http://code.google.com/p/pythonthreadpool/issues/detail?id=4
+                    #if (self.__active_workers == 0 or not self.__jobs.empty()):                    
+                        start_new_worker = True
+                        
+                self.__jobs.put(job)
+                
+                if (start_new_worker): 
+                    self.__new_worker()
+                    
+            except Exception:
+                raise AddJobException("Could not add job")
+        
+    
+    def get_job(self):
+        '''
+        Retrieve next job from queue 
+        workers die (and should) when 
+        returning None  
+        '''
+        
+        job = None
+        try:
+            if (self.__kill_workers_after < 0):
+                job = self.__jobs.get(True)
+            elif (self.__kill_workers_after == 0):
+                job = self.__jobs.get(False)
+            else:
+                job = self.__jobs.get(True, self.__kill_workers_after)
+        except Empty:
+            job = None
+        
+        return job

src/trimage/trimage.py

@@ -13,6 +13,8 @@ from hurry.filesize import *
 from imghdr import what as determinetype
 
 from Queue import Queue
+from ThreadPool import ThreadPool
+from multiprocessing import cpu_count
 
 from ui import Ui_trimage
 
@@ -308,23 +310,23 @@ class Image:
             shell = True, stdout=PIPE)
         if retcode == 0:
             self.newfilesize = QFile(self.fullpath).size()
-        return not retcode
+        self.retcode=retcode
+        return self
 
 class Worker(QThread):
 
     def __init__(self, parent=None):
         QThread.__init__(self, parent)
-        self.exiting = False
-        self.toProcess=Queue()
+        self.toDisplay=Queue()
+        self.threadpool = ThreadPool(max_workers=cpu_count())
 
     def __del__(self):
-        self.exiting = True
-        self.wait()
+        self.threadpool.shutdown()
 
     def compress_file(self, images, showapp, verbose, imagelist):
         """Start the worker thread."""
         for image in images:
-            self.toProcess.put(image)
+            self.threadpool.add_job(image.compress, None, return_callback=self.toDisplay.put)
         self.showapp = showapp
         self.verbose = verbose
         self.imagelist = imagelist
@@ -332,10 +334,10 @@ class Worker(QThread):
 
     def run(self):
         """Compress the given file, get data from it and call update_table."""
-        while self.showapp or not self.toProcess.empty():
-            image = self.toProcess.get()            
-            success=image.compress()
-            if success:                
+        tp = self.threadpool
+        while self.showapp or not (tp.__active_workers==0 and tp.__jobs.empty()):
+            image = self.toDisplay.get()
+            if image.retcode==0:
                 #calculate ratio and make a nice string
                 oldfilesizestr = size(image.oldfilesize, system=alternative)
                 newfilesizestr = size(image.newfilesize, system=alternative)