如何将数据从一个管道提供给三个不同的流程?
nulfp = open(os.devnull, "w")
piper = Popen([
"come command",
"some params"
], stdout = PIPE, stderr = nulfp.fileno())
pipe_consumer_1 = Popen([
"come command",
"some params"
], stdin = piper.stdout, stderr = nulfp.fileno())
pipe_consumer_2 = Popen([
"come command",
"some params"
], stdin = piper.stdout, stderr = nulfp.fileno())
pipe_consumer_3 = Popen([
"come command",
"some params"
], stdin = piper.stdout, stderr = nulfp.fileno())
pipe_consumer_1.communicate()
pipe_consumer_2.communicate()
pipe_consumer_3.communicate()
piper.communicate()
如果我运行上面的代码,它将产生一个损坏的文件。这意味着管道消费者可能没有从吹笛者那里读取全部输出。
这个工作正常,但速度慢得多:
nulfp = open(os.devnull, "w")
piper_1 = Popen([
"come command",
"some params"
], stdout = PIPE, stderr = nulfp.fileno())
piper_2 = Popen([
"come command",
"some params"
], stdout = PIPE, stderr = nulfp.fileno())
piper_3 = Popen([
"come command",
"some params"
], stdout = PIPE, stderr = nulfp.fileno())
pipe_consumer_1 = Popen([
"come command",
"some params"
], stdin = piper_1.stdout, stderr = nulfp.fileno())
pipe_consumer_2 = Popen([
"come command",
"some params"
], stdin = piper_2.stdout, stderr = nulfp.fileno())
pipe_consumer_3 = Popen([
"come command",
"some params"
], stdin = piper_3.stdout, stderr = nulfp.fileno())
pipe_consumer_1.communicate()
pipe_consumer_2.communicate()
pipe_consumer_3.communicate()
piper_1.communicate()
piper_2.communicate()
piper_3.communicate()
有关如何使第一个代码段与第二个代码段的工作方式相同的任何建议吗?如果我得到第一种工作方法,那么这个过程将在1/3的时间内完成。
答案 0 :(得分:2)
这只使用一个字节'块'但是你明白了。
from subprocess import Popen, PIPE
cat_proc = '/usr/bin/cat'
consumers = (Popen([cat_proc], stdin = PIPE, stdout = open('consumer1', 'w')),
Popen([cat_proc], stdin = PIPE, stdout = open('consumer2', 'w')),
Popen([cat_proc], stdin = PIPE, stdout = open('consumer3', 'w'))
)
with open('inputfile', 'r') as infile:
for byte in infile:
for consumer in consumers:
consumer.stdin.write(byte)
测试时,使用者输出文件与输入文件匹配。
编辑: 这是从1K块的过程中读取的。
from subprocess import Popen, PIPE
cat_proc = '/usr/bin/cat'
consumers = (Popen([cat_proc], stdin = PIPE, stdout = open('consumer1', 'w')),
Popen([cat_proc], stdin = PIPE, stdout = open('consumer2', 'w')),
Popen([cat_proc], stdin = PIPE, stdout = open('consumer3', 'w'))
)
producer = Popen([cat_proc, 'inputfile'], stdout = PIPE)
while True:
byte = producer.stdout.read(1024)
if not byte: break
for consumer in consumers:
consumer.stdin.write(byte)
答案 1 :(得分:1)
来自管道的数据只能读取一次,并且一旦读取就会从缓冲区中删除。这意味着消费者处理所有只会看到数据的随机部分,这些部分在组合时会提供完整的流。当然这对你来说不是很有用。
您可以让生产者进程写入subprocess.PIPE
,从块中读取数据块到缓冲区并将此缓冲区写入所有使用者进程。这意味着你必须自己完成所有的缓冲处理。使用tee
为您完成这项工作可能更容易 - 我将很快发布一些示例代码。