Oops. Sorry, that testing comment was for another changeset. I didn't
test your changes. If you think they could use some additional testing
on some more platforms, let me know.
thanks,
Chris
On 7/20/18 1:07 PM, Chris Plummer wrote:
Hi Ralf,
Changes look good and pass all the testing I did. You can push once
Serguei approves.
thanks,
Chris
On 7/20/18 7:28 AM, Schmelter, Ralf wrote:
Hi Sergue,
I’ve updated the webref:
http://cr.openjdk.java.net/~simonis/webrevs/2018/8205608.v4/
JVMTI_ERROR_OPAQUE_FRAME was never returned from GetFrameLocation().
If it would have, the old code would have removed all native methods
from the call stack. The original JVMDI call did indeed return
JVMDI_ERROR_OPAQUE_FRAME, so maybe it was a leftover from the
JVMDI->JVMTI transition.
I’ve tried to make the test more readable and added some comments to
explain why it is done the way it is.
Best regards,
Ralf
From: serguei.spit...@oracle.com [mailto:serguei.spit...@oracle.com]
Sent: Mittwoch, 18. Juli 2018 22:57
To: Chris Plummer <chris.plum...@oracle.com>; Schmelter, Ralf
<ralf.schmel...@sap.com>; serviceability-dev@openjdk.java.net;
Stuefe, Thomas <thomas.stu...@sap.com>
Subject: Re: RFR (S) 8205608: Fix 'frames()' in ThreadReferenceImpl.c
to prevent quadratic runtime behavior
Hi Ralf,
The fix itself looks pretty good to me.
Some minor comments.
The copyright year needs an update.
218 jint count, filledIn;
Could you, please, split the declarations above into different
lines to follow the local style?
Ii is interesting that the original implementation checked the error
code returned
from the JVMTI GetFrameLocation for being equal to
JVMTI_ERROR_OPAQUE_FRAME.
However, the GetFrameLocation spec does not list this error code as
possible.
Some comments about the test.
52 static void callEnded() {
53 System.out.println("SOE occurred as expected");
54 }
55
56 static int call(int depth) {
57 if (depth == 0) {
58 // Should have seen a stack overflow by now.
59 System.out.println("Exited without creating SOE");
60 System.exit(0);
61 }
62
63 try {
64 int newDepth = call(depth - 1);
65
66 if (newDepth == -1_000) {
67 // Pop some frames so there is room on the
stack for the
68 // println()
69 callEnded();
70 }
71
72 return newDepth - 1;
73 } catch (StackOverflowError e) {
74 return -1;
75 }
76 }
77 }
I'd suggest to rename the methods call() and callEnded() to
something like
recursiveMethod() and recursionEnd().
Also, the manipulations with SOE create a complexity and are
confusing.
Could it be more simple to let it propagated and then catch in
main()?
What is the point for all these checks at the lines 104-119?
In general, I'm looking for some ways to make it more clear,
simple and stable.
Thanks,
Serguei
