harmony-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Andrew Cornwall" <andrew.pack...@gmail.com>
Subject Re: [jira] Commented: (HARMONY-5900) [classlib][pack200] CpBands.parseCpSignature(Ljava/io/InputStream;) is hot
Date Tue, 08 Jul 2008 16:25:11 GMT
Sian, are we still using the DOMAIN_* code for ordering? I thought you'd
changed the code to use the ordering defined in the pack200 archive? If so,
we might be able to get rid of all the DOMAIN_ code.

    Andrew Jr.


On Tue, Jul 8, 2008 at 4:05 AM, Aleksey Shipilev <aleksey.shipilev@gmail.com>
wrote:

> Ah! IMO, that's ok in terms of performance.
> Anyway, we can implement Map storage for CpSignatures and have no
> degradation at all.
>
> Let's wait for Andrew.
>
> Thanks,
> Aleksey.
>
> On Tue, Jul 8, 2008 at 3:00 PM, Sian January <sianjanuary@googlemail.com>
> wrote:
> > I posted a suggested alternative on the JIRA, which doesn't do this
> search
> > at all and just uses the same objects for CpSignatures that were
> transmitted
> > in CpUtf8 if they exist.  The downside of this is that
> > CpBands.cpSignatureValue(..)
> > will always be searching a much larger map, so I'm not sure if there are
> > performance implications from that.  I'm also not 100% sure that we don't
> > need the code I've taken out, but Andrew might be able to answer that.
> >
> > On 08/07/2008, Aleksey Shipilev <aleksey.shipilev@gmail.com> wrote:
> >>
> >> This method is the hell for performance.
> >> It is not only accounts for 15% of CPU time, but instrumentation also
> >> shows:
> >> - average size of array is 4700 elements
> >> - 99% times the search traverses entire array and finds nothing
> >>
> >> We should consider move to *Map here :)
> >>
> >> Thanks,
> >> Aleksey.
> >>
> >> On Tue, Jul 8, 2008 at 1:30 PM, Sian January <
> sianjanuary@googlemail.com>
> >> wrote:
> >> > The purpose of this code is to get the class constant pool ordering
> >> right,
> >> > so that if a signature string has already been transmitted in the
> CpUtf8
> >> > band it has the correct global index.  However it might be possible to
> do
> >> > the search a different way if this method is taking a long time.  E.g
> if
> >> I
> >> > get rid of the code that differentiates between signatures and other
> >> Ascii
> >> > values (i.e. replace all occurrences of
> >> > ClassConstantPool.DOMAIN_SIGNATUREASCIIZ
> >> > with ClassConstantPool.DOMAIN_NORMALASCIIZ) then my tests seem to
> pass,
> >> > although Andrew you wrote that code so it might be that I'm not
> testing
> >> all
> >> > the cases where this is needed.  Also there might be worse performance
> >> > implications from making that change, but I can attach a patch to the
> >> JIRA
> >> > if you would like to test it.
> >> >
> >> >
> >> >
> >> > On 08/07/2008, Aleksey Shipilev (JIRA) <jira@apache.org> wrote:
> >> >>
> >> >>
> >> >>    [
> >> >>
> >>
> https://issues.apache.org/jira/browse/HARMONY-5900?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12611488#action_12611488
> >> ]
> >> >>
> >> >> Aleksey Shipilev commented on HARMONY-5900:
> >> >> -------------------------------------------
> >> >>
> >> >> From my measurements for 20Mb .jar.pack.gz file on Sun JDK 1.6.0_05
> >> >> -server, CPBands.search accounts for 15% of CPU time.
> >> >> Let's move the discussion to dev.
> >> >>
> >> >> > [classlib][pack200] CpBands.parseCpSignature(Ljava/io/InputStream;)
> is
> >> >> hot
> >> >> >
> >> >>
> >>
> --------------------------------------------------------------------------
> >> >> >
> >> >> >                 Key: HARMONY-5900
> >> >> >                 URL:
> >> https://issues.apache.org/jira/browse/HARMONY-5900
> >> >> >             Project: Harmony
> >> >> >          Issue Type: Wish
> >> >> >          Components: Classlib
> >> >> >    Affects Versions: 5.0M6
> >> >> >         Environment: All Pack200 HEAD
> >> >> >            Reporter: Andrew Cornwall
> >> >> >
> >> >> > The method
> >> >>
> >>
> org/apache/harmony/unpack200/CpBands.parseCpSignature(Ljava/io/InputStream;)
> >> >> appears to be very hot. I tried initially to optimize it by caching
> some
> >> of
> >> >> its arrays:
> >> >> >     static void clearArrayCache() {
> >> >> >       arrayCache = new SegmentConstantPoolArrayCache();
> >> >> >     }
> >> >> >
> >> >> >     private static SegmentConstantPoolArrayCache arrayCache =
new
> >> >> SegmentConstantPoolArrayCache();
> >> >> >
> >> >> >     private int search(String[] array, String string) {
> >> >> >       if(array.length > 30) {
> >> >> >               List indexes = arrayCache.indexesForArrayKey(array,
> >> >> string);
> >> >> >               if (indexes.size() == 0) {
> >> >> >                       return -1;
> >> >> >               }
> >> >> >               return ((Integer)indexes.get(0)).intValue();
> >> >> >       } else {
> >> >> >               for (int i = 0; i < array.length; i++) {
> >> >> >                       if(array[i].equals(string)) {
> >> >> >                               return i;
> >> >> >                       }
> >> >> >               }
> >> >> >               return -1;
> >> >> >       }
> >> >> >     }
> >> >> > ... but that didn't appear to increase performance. (Maybe all
the
> >> >> searches are done once?)
> >> >> > Any ideas how to tune parseCpSignature to get it faster?
> >> >>
> >> >> --
> >> >> This message is automatically generated by JIRA.
> >> >> -
> >> >> You can reply to this email to add a comment to the issue online.
> >> >>
> >> >>
> >> >
> >> >
> >> > --
> >> > Unless stated otherwise above:
> >> > IBM United Kingdom Limited - Registered in England and Wales with
> number
> >> > 741598.
> >> > Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6
> >> 3AU
> >> >
> >>
> >
> >
> >
> > --
> > Unless stated otherwise above:
> > IBM United Kingdom Limited - Registered in England and Wales with number
> > 741598.
> > Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6
> 3AU
> >
>

Mime
  • Unnamed multipart/alternative (inline, None, 0 bytes)
View raw message