Wei Feng Niu wrote:
Hi,
I have a target to detect whether a port is listening, like the
following:
================================================================
<project name="test" default="test.server">
<target name="test.server" description="Test server.">
<echo message="trying to test server at localhost:39001..." />
<waitfor maxwait="300" maxwaitunit="second" checkevery="5"
timeoutproperty="server.not.started">
<and>
<socket server="localhost" port="39001" />
</and>
</waitfor>
<fail message="server did not start!" if="server.not.started" />
<echo message="server has started successfully." />
</target>
</project>
=================================================================
Put the codes into a build file and run it, I got the following result:
ant -f t.xml;netstat -an|grep 39001
Buildfile: t.xml
test.server:
[echo] trying to test server at localhost:39001...
[echo] server has started successfully.
BUILD SUCCESSFUL
Total time: 59 seconds
tcp 0 0 ::ffff:127.0.0.1:39001 ::ffff:127.0.0.1:39001
TIME_WAIT
Thoug there is no any server on 39001 started, after a while the target
will return with "server has started successfully". It is very strange.
Seems the <socket> task makes a listener on 39001 and detect it. So far
I just found the problem on RedHat Linux. And the time that <socket>
returns are different every time you run the target. Sometimes the
target works as expected and sometimes works as above.
Does anybody know what's the cause? Thanks
1. <socket> tries to open a TCP connection; it gets assigned some random
port..I'd be surprised that it got 39001, though it is a high enough
value it could happen sometimes. Maybe it depends where the TCP stack
starts allocating unallocated ports. Try opening a socket to a remote
site, see what gets opened there.
2. run netstat -p to see the process with the port
3. are you sure the port is closed? Sometimes after a previous run the
port may still be open.
-steve
2.
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