On 7/08/2012 1:03 PM, Frank Ding wrote:
Hi Holmes,
David :)
It is not only when -Xrs is specified. The circumstances can be
illustrated below
1. a JVM has its own extra signal registration that occupies say, "INT",
prior to the execution Terminator.setup().
2. User customizes HotSpot to have similar overridden signal handling.
In both cases, I think Terminator.setup() should work at best effort to
register all.
The change is harmless but as far as I can see you would have to
customize the VM before this change would have any affect. The signals
involved here are the SHUTDOWNn_SIGNAL values (which for linux/solaris
are HUP, INT and TERM). JVM_RegisterSignal simply does:
case SHUTDOWN1_SIGNAL:
case SHUTDOWN2_SIGNAL:
case SHUTDOWN3_SIGNAL:
if (ReduceSignalUsage) return (void*)-1;
if (os::Linux::is_sig_ignored(sig)) return (void*)1;
}
So with -Xrs all values will get rejected as a group. As far as I can
see this is the only time that -1 will be returned to Signal.handle0 and
hence the only circumstance where IllegalArgumentException will be
thrown. So without customizing the VM if any of these signals cause
IllegalArgumentException then they all will and hence having distinct
try/catch blocks for each is pointless.
Did I miss something?
David
-----
Best regards,
Frank
On 8/6/2012 7:08 PM, David Holmes wrote:
On 6/08/2012 6:57 PM, Frank Ding wrote:
Hi Holmes,
I agree with your comment on duplicated comment. It should be
factored out.
The context of the change is that the group of signal handlers should be
registered at best effort, which means for all JVM, we should try to
register them all in an independent way. In fact, the original code does
not act homogeneously. For example, in
solaris/classes/java/lang/Terminator.java, there are 3 registration
calls for signal "HUP", "INT" and "TERM". On start up of some JVM, "INT"
may already have been occupied for some reason and this will cause
"TERM" to be skipped. It is not what the original code intends to do, is
it?
My question is: exactly what circumstances will cause the
IllegalArgumentException to be thrown? Is it only when -Xrs is
specified? And if so does it then affect all of the signals?
David
------
I provided a new revision of patch to remove the dup comment, available
@ http://cr.openjdk.java.net/~youdwei/ojdk-430/webrev.01/. Your comment
is much appreciated.
Thanks and best regards,
Frank
On 8/6/2012 9:51 AM, David Holmes wrote:
Hi Frank,
On 3/08/2012 5:39 PM, Frank Ding wrote:
Hi guys,
I found that in java.lang.Terminator, setup() method,
The following code of registering default signal handlers can be
improved:
/ try {
Signal.handle(new Signal("INT"), sh);
Signal.handle(new Signal("TERM"), sh);
} catch (IllegalArgumentException e) {
}/
The revised code is illustrated below:
/ try {
Signal.handle(new Signal("INT"), sh);
} catch (IllegalArgumentException e) {
}
try {
Signal.handle(new Signal("TERM"), sh);
} catch (IllegalArgumentException e) {
}
/The improved version makes more sense since exception thrown from
first
Signal.handle call does not affect subsequent calls. This is more
consistent with its original intention.
A patch I made is available @
http://cr.openjdk.java.net/~youdwei/ojdk-430/webrev.00//
/Could anybody please take a look at it? Thanks in advance/
Can you explain the context for this change. It seems to me that there
is an expectation that the group of signals act homogenously: all or
none, whereas your change make it appear that the success/failure for
each signal is independent. Understanding exactly when/why the
IllegalArgumentException is thrown is important here.
I don't like seeing the duplicated comment, perhaps that can be
factored out to the head of the block of code?
Thanks,
David Holmes
Best regards,
Frank
/
