hotspot.log overlapping log statements (JITWatch) (original) (raw)

David Holmes david.holmes at oracle.com
Wed Feb 26 19:03:16 PST 2014

On 27/02/2014 3:21 AM, John Rose wrote:

On Feb 26, 2014, at 4:35 AM, David Holmes <david.holmes at oracle.com_ _<mailto:david.holmes at oracle.com>> wrote:

I really didn't follow how you could untangle arbitrary non-delimited text, but I think it will still require changes to the use of the print functions to fix it - right? Logically what we want is per-thread buffering so that we only do a write() of a full line of text. The log is line-oriented, so switching threads in the middle of a line requires that extra info.

Line-oriented in that we always start a new line when we switch threads

You could queue up threads until the writer has finished his line but I'd rather not, given that lines might require internal computation.

That's why I said per-thread buffering (not that I see a way to implement it). No-one blocks but no thread starts to write a line until it has a full line to write.

It's better (IMO) to push the work to decode/reassemble after the JVM exits.

Here's approximately what I had in mind: diff --git a/src/share/vm/utilities/ostream.cpp b/src/share/vm/utilities/ostream.cpp --- a/src/share/vm/utilities/ostream.cpp +++ b/src/share/vm/utilities/ostream.cpp @@ -961,7 +961,11 @@ // got the lock if (writerid != lastwriter) { if (haslog) { - logfile->bol(); + int pos = logfile->position(); + if (pos > 0) { + logfile->bol(); + logfile->printcr("", pos); + } // output a hint where this output is coming from: logfile->printcr("", writerid); }

I see.

David

The "pos" bit is redundant, an extra clue about trailing spaces.

— John

More information about the hotspot-dev mailing list