Python - GPSD在非线程池中的使用

Question

我正在使用python实现一个GPSD轮询:遵循这里的python示例：http://www.catb.org/gpsd/client-howto.html#_python_examples

我不能使用这里的代码是有原因的：https://gist.github.com/wolfg1969/4653340，因为我必须在我的系统中对大约10个进程进行守护进程，所以为了便于实现，我会使用catb进程。

我有一个关于以下代码的问题，为什么它在两个周期后停止？我该怎么解决这个问题呢？谢谢。

def GpsDetection():

global gpsd
gpsd = gps(mode=WATCH_ENABLE)

try:
    while 1:
        # Do stuff
        report = gpsd.next()
        # Check report class for 'DEVICE' messages from gpsd.  If we're expecting messages from multiple devices we should
        # inspect the message to determine which device has just become available.  But if we're just listening
        # to a single device, this may do.
        print report
        if report['class'] == 'DEVICE':
            # Clean up our current connection.
            gpsd.close()
            # Tell gpsd we're ready to receive messages.
            gpsd = gps(mode=WATCH_ENABLE)
        # Do more stuff
        print "GPSD Data is showing now!!!!!!!!!!!!!!!!!!!!!!!!!!!!"
        print datetime.datetime.now()
        print 'latitude    ' , gpsd.fix.latitude
        print 'longitude   ' , gpsd.fix.longitude
        print 'time utc    ' , gpsd.utc,' + ', gpsd.fix.time
        print 'altitude (m)' , gpsd.fix.altitude
        print 'eps         ' , gpsd.fix.eps
        print 'epx         ' , gpsd.fix.epx
        print 'epv         ' , gpsd.fix.epv
        print 'ept         ' , gpsd.fix.ept
        print 'speed (m/s) ' , gpsd.fix.speed
        print 'climb       ' , gpsd.fix.climb
        print 'track       ' , gpsd.fix.track
        print 'mode        ' , gpsd.fix.mode
        print                  
        print 'sats        ' , gpsd.satellites

        time.sleep(1)
except StopIteration:
    print "GPSD has terminated"

return

Answer 1

由于这个问题，我很好奇如何处理gpsd中的JSON数据，以满足较低或较慢的gps定位要求。

如果客户端与gpsd通信的套接字填满、未被读取或转储，则gpsd关闭该套接字。

我听说在4800波特的时候一秒内会发生很多事情。毫不奇怪，守护进程在大约8到15秒内放弃了一个完整的缓冲区，或者每当它超时的时候。

我写了a threading shim for a Python 2-3 gpsd client

这和the python client，需要导入机制和睡眠来减慢它，如果没有其他东西。

from time import sleep
from agps3threaded import AGPS3mechanism

agps_thread = AGPS3mechanism()  # Instantiate AGPS3 Mechanisms
agps_thread.stream_data(host='192.168.0.4')  # From localhost (), or other hosts, by example, (host='gps.ddns.net')
agps_thread.run_thread(usnap=.2)  # Throttle the time to sleep after an empty lookup, default 0.2 two tenths of a second

while True:  # All data is available via instantiated thread data stream attribute.
# line #140-ff of /usr/local/lib/python3.5/dist-packages/gps3/agps.py
    print('-----')
    print(agps_thread.data_stream.time)
    print('Lat:{}'.format(agps_thread.data_stream.lat))
    print('Lon:{}'.format(agps_thread.data_stream.lon))
    print('Speed:{}'.format(agps_thread.data_stream.speed))
    print('Course:{}'.format(agps_thread.data_stream.track))
    print('-----')
    sleep(30)

这将解决您的线程化gpsd数据问题。

如果您想知道about代码不工作的原因，它在哪里中断或停止，以及错误消息是什么？