Preliminary review: Adding tracing of I/O calls (original) (raw)

Remi Forax forax at univ-mlv.fr
Fri Nov 2 21:03:06 UTC 2012

On 11/02/2012 09:49 PM, Staffan Larsen wrote:

Thanks, Jim. I'll come back with micro-benchmark numbers.

/Staffan

I think this code is a good candidate for the almost final design pattern :) http://weblogs.java.net/blog/forax/archive/2011/12/17/jsr-292-goodness-almost-static-final-field

Basically you want a volatile value that becomes final so it can be optimized by the VM.

cheers, Rémi

On 2 nov 2012, at 21:27, Jim Gish <jim.gish at oracle.com> wrote:

Hi Staffan,

This looks fine to me as well, but I had the same question as Mandy about performance. Given the sensitivity to changes in I/O it would be good to have some micro-benchmarks here. Thanks, Jim On 11/02/2012 04:12 PM, Mandy Chung wrote: Hi Staffan,

On 11/2/2012 11:36 AM, Staffan Larsen wrote: This is a preliminary review request for adding an API for tracing I/O calls. For now, this is an empty infrastructure intended to enable diagnosing/tracing of i/o calls. A user of the API can register a listener and get callbacks for read and write operations on sockets and files. It does not (yet) cover asynchronous i/o calls. When not used, the implementation should add a minimum of overhead. To provide useful information to the user, FileInputStream, FileOutputStream and RandomAccessFile have been modified to keep track of the path they operate on (when available).

Webrev: http://cr.openjdk.java.net/~sla/iotrace/webrev.00/ This looks okay to me. Minor comments: sun/misc/IoTrace.java L36: should it be volatile in case another thread is setting to another listener? The *Begin() methods return a "handle" that will be passed to the *End() methods. Have you considered to define a type for it rather than Object? Do you have any performance measurement result that you can share? As for the unit tests, I know you have tests written for the feature that implements the listeners. I wonder if it's worth adding some sanity tests along with this change? Mandy Feedback is most welcome, /Staffan -- Jim Gish | Consulting Member of Technical Staff | +1.781.442.0304 Oracle Java Platform Group | Core Libraries Team 35 Network Drive Burlington, MA 01803 jim.gish at oracle.com

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