Commit c9772570 authored by Sascha Silbe's avatar Sascha Silbe Committed by Fam Zheng
Browse files

docker.py: don't hang on large docker output 



Unlike Popen.communicate(), subprocess.call() doesn't read from the
stdout file descriptor. If the child process produces more output than
fits into the pipe buffer, it will block indefinitely.

If we don't intend to consume the output, just send it straight to
/dev/null to avoid this issue.

Signed-off-by: default avatarSascha Silbe <silbe@linux.vnet.ibm.com>
Reviewed-by: default avatarJanosch Frank <frankja@linux.vnet.ibm.com>
Message-Id: <1473192351-601-2-git-send-email-silbe@linux.vnet.ibm.com>
Signed-off-by: default avatarFam Zheng <famz@redhat.com>
parent 9af4c174

tests/docker/docker.py

+6 −3
Original line number Diff line number Diff line
@@ -25,6 +25,10 @@ from tarfile import TarFile, TarInfo 
from StringIO import StringIO

from shutil import copy, rmtree





DEVNULL = open(os.devnull, 'wb')





def _text_checksum(text):

    """Calculate a digest string unique to the text content"""

    return hashlib.sha1(text).hexdigest()
@@ -34,8 +38,7 @@ def _guess_docker_command(): 
    commands = [["docker"], ["sudo", "-n", "docker"]]

    for cmd in commands:

        if subprocess.call(cmd + ["images"],

                           stdout=subprocess.PIPE,

                           stderr=subprocess.PIPE) == 0:

                           stdout=DEVNULL, stderr=DEVNULL) == 0:

            return cmd

    commands_txt = "\n".join(["  " + " ".join(x) for x in commands])

    raise Exception("Cannot find working docker command. Tried:\n%s" % \
@@ -98,7 +101,7 @@ class Docker(object): 


    def _do(self, cmd, quiet=True, infile=None, **kwargs):

        if quiet:

            kwargs["stdout"] = subprocess.PIPE

            kwargs["stdout"] = DEVNULL

        if infile:

            kwargs["stdin"] = infile

        return subprocess.call(self._command + cmd, **kwargs)