Raspberry Pi上的多线程Python程序中非常缓慢的二进制文件下载

2024-03-29 08:22:09 发布

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我正在Raspberry Pi 4上编写一个多线程Python应用程序,偶尔需要从服务器下载约200 KB的二进制文件,在测试期间,服务器是我在本地网络上的笔记本电脑。我已经使用Curl或Python 3 CLI requests.get调用在RPi上验证了我的笔记本电脑在大约一秒钟内就提供了这些文件,但是在我的应用程序中,请求下载调用在完成之前至少会挂起2分钟。受影响的代码如下所示:

# requests current composite from server 
# args:     timestamp: timestamp of last update
# returns:  SUCCESS_RETURN if updated, NONE_RETURN otherwise, OFFLINE_RETURN on failure to connect

def getcomposite(self, timestamp=None):
    try:
        self.slplogger.info("Downloading composite for timestamp %s" % (dt.utcfromtimestamp(timestamp).strftime("%Y-%m-%d-%H:%M:%S") if timestamp else "None"))

        # HANGS HERE
        compositeresp = requests.post(SERVER_URL + "getcomposite", data={'mac' : self.mac, 'timestamp' : timestamp})

        self.slplogger.info("Downloaded new composite: %s" % str(compositeresp.text[:min(10, len(compositeresp.text))]))

        if compositeresp.text != NONE_RETURN and compositeresp.content:
            with self.compositelock:
                self.compositedata = np.load(BytesIO(compositeresp.content), allow_pickle=False)
                # compute new input norm for adding subsequent input
                self.compositenorm = np.mean(self.compositedata[:]['value'], dtype=int)
                self.emptycomposite = False
                self.slplogger.info("Set new composite: %s" % str(self.compositedata[:min(10, len(self.compositedata))]))
            return SUCCESS_RETURN
        return FAILURE_RETURN
    except requests.exceptions.ConnectionError:

        self.slplogger.info("Composite download failed. Unable to connect to server")
        return OFFLINE_RETURN

这里定义了调用此方法的非守护进程线程(复合轮询间隔为2秒):

# --------------------------------------------------------------------
#   CompositePollingThread - Thread superclass that periodically 
#   polls strangeloop server for new additions to the composite loop
# --------------------------------------------------------------------

class CompositePollingThread(Thread):

    # overloaded Thread constructor
    # args:     pedal: parent Pedal object that instantiated this thread

    def __init__(self, pedal):
        Thread.__init__(self)
        self.stop = Event()
        self.pedal = pedal
        self.timestamp = None

        self.pedal.slplogger.debug("Initialized composite polling thread")

    # main thread execution loop

    def run(self):

        self.pedal.slplogger.debug("Started composite polling thread")

        while self.pedal.running:
            time.sleep(COMPOSITE_POLL_INTERVAL)

            # timestamp to determine whether any new data needs to be downloaded
            if not self.pedal.recording and self.pedal.getcomposite(timestamp=self.timestamp) == SUCCESS_RETURN:
                self.timestamp = dt.utcnow().timestamp()

                self.pedal.slplogger.debug("Downloaded new composite at %s" % dt.utcfromtimestamp(self.timestamp).strftime("%Y-%m-%d-%H:%M:%S"))

        self.pedal.slplogger.debug("Ended composite polling thread")

我假设下载速度慢是由于程序中的线程问题造成的。它还负责处理占用大部分CPU的实时输入。我能做些什么来提高下载速度吗?有没有办法给线程更高的优先级,或者我应该切换到多处理模块来利用RPI4的多核


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1楼 · 发布于 2024-03-29 08:22:09

最后,问题出在服务器上。我将端点响应从一个“flask.send_文件”更改为一个简单的flask.response对象,其中包含我所需的数据(类似于Serve image stored in SQLAlchemy LargeBinary column),现在它可以在不到十秒钟的时间内下载。我不知道为什么下载只在通过程序访问时(与CLI请求相反)花费了这么长时间,但这一更改解决了它

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