Hi Chris,
On 15/09/2017 2:19 PM, Chris Plummer wrote:
On 9/14/17 9:56 AM, Chris Plummer wrote:
On 9/14/17 1:45 AM, David Holmes wrote:
On 14/09/2017 5:53 PM, Dmitry Samersoff wrote:
Chris,
So now .attach_pid<pid> is always created in cwd as you can see in
createAttachFile(), although AttachListener::is_init_trigger() does
check tmp, but only after cwd.
***getNamespacePid - ns_pid: 125
***findSocketFile - f: /proc/24445/root/tmp/.java_pid125
***createAttachFile - path: /proc/24445/cwd/.attach_pid125
Could we always use tmp ?
IMHO cwd is not a right choice for such kind of files, it should be
either $HOME or tmp.
And we hardwired /tmp and stopped using cwd under
https://bugs.openjdk.java.net/browse/JDK-7132199
So I'm a bit confused as to how this has evolved back into using cwd. ??
Yeah, I had this backwards with my earlier comment. Before JDK-7132199
we actually do it the way we do now, trying cwd first, and then tmp if
it fails. JDK-7132199 made it only use tmp, but only for
findSocketFile(). createAttachFile() still tries cwd first and then
tmp, and I see nothing in the history to indicate this was ever
changed, other than to force the location of tmp to /tmp with
JDK-6950927.
So the question is do we get rid of the cwd support and always use
tmp? If yes, I think it's best not to do that as part of this CR. I'd
rather just add the docker /tmp support to createAttachFile() now, and
have a separate CR deal with removing all cwd support (or maybe even
push changes for it before the docker support fix).
Here's an updated webrev with the tmpdir fix in createAttachFile():
http://cr.openjdk.java.net/~cjplummer/8179498/webrev.02/webrev_jdk/
I ran all the same tests again, including testing with docker. To make
sure it was hitting the tmpdir code, I forced the cwd code to error out
by making it use cwdX instead.
There are also two other changes to fix an issue I noticed when you
provide a bad pid. You are suppose to get an error message like this:
java.io.IOException: No such process
at jdk.attach/sun.tools.attach.VirtualMachineImpl.sendQuitTo(Native
Method)
at
jdk.attach/sun.tools.attach.VirtualMachineImpl.<init>(VirtualMachineImpl.java:80)
at
jdk.attach/sun.tools.attach.AttachProviderImpl.attachVirtualMachine(AttachProviderImpl.java:58)
at
jdk.attach/com.sun.tools.attach.VirtualMachine.attach(VirtualMachine.java:207)
at jdk.jcmd/sun.tools.jcmd.JCmd.executeCommandForPid(JCmd.java:114)
at jdk.jcmd/sun.tools.jcmd.JCmd.main(JCmd.java:98)
However, I was seeing the following due to the docker related changes:
java.nio.file.NoSuchFileException: /proc/7777/status
at
java.base/sun.nio.fs.UnixException.translateToIOException(UnixException.java:92)
at
java.base/sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:111)
at
java.base/sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:116)
at
java.base/sun.nio.fs.UnixFileSystemProvider.newByteChannel(UnixFileSystemProvider.java:215)
at java.base/java.nio.file.Files.newByteChannel(Files.java:369)
at java.base/java.nio.file.Files.newByteChannel(Files.java:415)
at
java.base/java.nio.file.spi.FileSystemProvider.newInputStream(FileSystemProvider.java:384)
at java.base/java.nio.file.Files.newInputStream(Files.java:154)
at java.base/java.nio.file.Files.newBufferedReader(Files.java:2830)
at java.base/java.nio.file.Files.readAllLines(Files.java:3260)
at
jdk.attach/sun.tools.attach.VirtualMachineImpl.getNamespacePid(VirtualMachineImpl.java:334)
at
jdk.attach/sun.tools.attach.VirtualMachineImpl.<init>(VirtualMachineImpl.java:71)
at
jdk.attach/sun.tools.attach.AttachProviderImpl.attachVirtualMachine(AttachProviderImpl.java:58)
at
jdk.attach/com.sun.tools.attach.VirtualMachine.attach(VirtualMachine.java:207)
at jdk.jcmd/sun.tools.jcmd.JCmd.executeCommandForPid(JCmd.java:114)
at jdk.jcmd/sun.tools.jcmd.JCmd.main(JCmd.java:98)
I fixed getNamespacePid() to validate that /proc/<pid>/status exists
before trying to process it. If it doesn't, it just returns pid rather
than trying to find ns_pid. However, that led to:
java.io.IOException: No such file or directory
at java.base/java.io.UnixFileSystem.createFileExclusively(Native
Method)
at java.base/java.io.File.createNewFile(File.java:1024)
at
jdk.attach/sun.tools.attach.VirtualMachineImpl.createAttachFile(VirtualMachineImpl.java:300)
at
jdk.attach/sun.tools.attach.VirtualMachineImpl.<init>(VirtualMachineImpl.java:78)
at
jdk.attach/sun.tools.attach.AttachProviderImpl.attachVirtualMachine(AttachProviderImpl.java:58)
at
jdk.attach/com.sun.tools.attach.VirtualMachine.attach(VirtualMachine.java:207)
at jdk.jcmd/sun.tools.jcmd.JCmd.executeCommandForPid(JCmd.java:114)
at jdk.jcmd/sun.tools.jcmd.JCmd.main(JCmd.java:98)
This is because createAttachFile() first tried to create the file in
/proc/<pid>/cwd, and after that failed with IOException (which is
caught), it tried in /proc/<pid>/root/tmp, which fails with the above
uncaught IOException. I changed the code to only try
/proc/<pid>/root/tmp if pid != ns_pid (which means either it is a docker
situation and the pid is valid). Otherwise it reverts to the old
behavior just using /tmp.
This all seems okay.
One suggestion:
359 } catch (NumberFormatException | IOException x) {
360 throw new AttachNotSupportedException("Unable to parse
namespace");
361 }
Set "x" as the cause of the AttachNotSupportedException before throwing
it. That will give more diagnostics if we ever see this exception.
Thans,
David
thanks,
Chris
thanks,
Chris
David
-Dmitry
On 14.09.2017 07:15, Chris Plummer wrote:
On 9/13/17 9:00 PM, David Holmes wrote:
Hi Chris,
On 14/09/2017 1:03 PM, Chris Plummer wrote:
Hi David,
On 9/13/17 5:12 PM, David Holmes wrote:
Hi Chris,
On 14/09/2017 8:23 AM, Chris Plummer wrote:
I could use one more reviewer.
Generally this seems okay to me.
One query though ... in createAttachFile don't you need to alter
the
tmpdir using part in a similar manner to how findSocketFile was
modified?
The fix in findSocketFile is not just to make sure the client uses
the correct pid in the .java_pid file files, but also (as you point
out) to make sure that the client properly references the target
jvm's tmp directory when accessing the .java_pid file.
findSocketFile
is a little
I presume you mean createAttachFile there.
Yes.
different. You still have to map to the proper from pid to ns_pid
when referencing the .attach_pid file, but you don't have the /tmp
mount point differences to deal with. /proc/<pid>/cwd should work
even if the pid is for a docker. You don't even have to map to the
pid as the docker sees it. /proc/<pid>/cwd from the client's POV
should be the same as /proc/<ns_pid>/cwd from the target JVM's POV.
Sorry but I don't follow. If findSocketFile has to look in
/proc/<pid>/root/<tmpdir> for the socket file, why does the
createAttachFile not also have to write the attach file into
/proc/<pid>/root/<tmpdir> ?? In both cases it needs to find the
tmpdir
of the target process.
Fortunately I have some old printlns that might help:
***getNamespacePid - ns_pid: 125
***findSocketFile - f: /proc/24445/root/tmp/.java_pid125
***createAttachFile - path: /proc/24445/cwd/.attach_pid125
So this is a case where the real pid is 24445, but the namespace
pid in
the docker is 125. The docker can (and does) reference
/tmp/.java_pid125, but the client needs to reference
/proc/24445/root/tmp/.java_pid125 to get to the same file. For
.attach_pid125, the client can get to it through
/proc/24445/cwd/.attach_pid125, and the docker process will look in
cwd
for the file. This is done in AttachListener::is_init_trigger().
BTW, comments like the following are no longer correct due to
JDK-7132199:
// "/tmp" is used as a global well-known location for the files
// .java_pid<pid>. and .attach_pid<pid>. It is important that
this
// location is the same for all processes, otherwise the tools
// will not be able to find all Hotspot processes.
// Any changes to this needs to be synchronized with HotSpot.
private static final String tmpdir = "/tmp";
So now .attach_pid<pid> is always created in cwd as you can see in
createAttachFile(), although AttachListener::is_init_trigger() does
check tmp, but only after cwd.
thanks,
Chris
Thanks,
David
Minor note - you can collapse your catch blocks into 1 using
something like
������� } catch (NumberFormatException | IOException x) {
������������ throw new AttachNotSupportedException("Unable to parse
namespace");
������� }
I'll make that change.
thanks,
Chris
Cheers,
David
thanks,
Chris
On 9/11/17 8:03 PM, Chris Plummer wrote:
Ok, I will. Thanks.
Chris
On 9/11/17 6:13 PM, [email protected] wrote:
Hi Chris,
This looks good to me.
I'm not sure if all the nsk.aod and the AttachOnDemand tests
from
the nsk.jvmti are run in the hotspot tier1, 2, and 3 tests.
It makes sense to double-check it.
Thanks,
Serguei
On 9/10/17 20:34, Chris Plummer wrote:
[re-sending - sent to wrong alias first time]
Hello,
Please review the following:
https://bugs.openjdk.java.net/browse/JDK-8179498
http://cr.openjdk.java.net/~cjplummer/8179498/webrev.00/webrev_jdk/
The CR has the relevant details. Some previous discussions can
be found here:
http://mail.openjdk.java.net/pipermail/serviceability-dev/2017-April/021237.html
http://mail.openjdk.java.net/pipermail/serviceability-dev/2017-May/021249.html
http://mail.openjdk.java.net/pipermail/serviceability-dev/2017-August/021679.html
Testing with docker has been limited to just making sure jcmd
now works with the docker setup I was provided. I currently
don't see how we can run our existing tests in a way that would
test the docker support without doing some rewriting of the
tests.
I also ran all our hotspot tier1, 2, and 3 tests, along with
jdk/test/tools and jdk/test/sun/tools tests to make sure
existing functionality is not broken with these changes.
thanks,
Chris
