Re: GetPrimitiveArrayCritical vs GetByteArrayRegion: 140x slow-down using -Xcheck:jni and java.util.zip.DeflaterOutputStream

Hi, On Fri, 2018-03-16 at 17:19 +, Ian Rogers wrote: > Thanks Paul, very interesting. > > On Fri, Mar 16, 2018 at 9:21 AM Paul Sandoz > wrote: > > Hi Ian, Thomas, > > > > [...] > > (This is also something we need to consider if we modify buffers to > > support

Re: GetPrimitiveArrayCritical vs GetByteArrayRegion: 140x slow-down using -Xcheck:jni and java.util.zip.DeflaterOutputStream

Hi Ian, Thomas, Some background on the bulk copying for byte buffers after talking with Mikael who worked on these changes a few years ago. Please correct the following if needed as our memory is hazy :-) IIRC at the time we felt this was a reasonable thing to do because C2 did not strip mine

Re: GetPrimitiveArrayCritical vs GetByteArrayRegion: 140x slow-down using -Xcheck:jni and java.util.zip.DeflaterOutputStream

Hi, On Thu, 2018-03-15 at 01:00 +, Ian Rogers wrote: > An old data point on how large a critical region should be comes from > java.nio.Bits. In JDK 9 the code migrated into unsafe, but in JDK 8 > the copies within a critical region were bound at most copying 1MB: >

Re: GetPrimitiveArrayCritical vs GetByteArrayRegion: 140x slow-down using -Xcheck:jni and java.util.zip.DeflaterOutputStream

Thanks Ian and Sherman for the excellent presentation and memories of ancient efforts. Yes, Sherman, I still have vague memory that attempts to touch any implementation detail in this area was asking for trouble and someone would complain. I was happy to let you deal with those problems!

Re: GetPrimitiveArrayCritical vs GetByteArrayRegion: 140x slow-down using -Xcheck:jni and java.util.zip.DeflaterOutputStream

On 3/5/18, 12:45 PM, Xueming Shen wrote: On 3/5/18, 11:15 AM, Ian Rogers wrote: Thanks! Changing the DeflaterOutputStream buffer size to be something other than the default reduces the number of JNI native calls and is a possible work around here, as this is an implementation detail could it

Re: GetPrimitiveArrayCritical vs GetByteArrayRegion: 140x slow-down using -Xcheck:jni and java.util.zip.DeflaterOutputStream

On 3/5/18, 11:15 AM, Ian Rogers wrote: Thanks! Changing the DeflaterOutputStream buffer size to be something other than the default reduces the number of JNI native calls and is a possible work around here, as this is an implementation detail could it be made in the JDK? Unfortunately larger

Re: GetPrimitiveArrayCritical vs GetByteArrayRegion: 140x slow-down using -Xcheck:jni and java.util.zip.DeflaterOutputStream

On 03/05/2018 10:28 AM, Xueming Shen wrote: On 03/05/2018 08:34 AM, Ian Rogers wrote: Firstly, we're not running -Xcheck:jni in production code :-) During development and testing it doesn't seem an unreasonable flag to enable, but a 140x regression is too much to get developers to swallow.

Re: GetPrimitiveArrayCritical vs GetByteArrayRegion: 140x slow-down using -Xcheck:jni and java.util.zip.DeflaterOutputStream

On 03/05/2018 08:34 AM, Ian Rogers wrote: Firstly, we're not running -Xcheck:jni in production code :-) During development and testing it doesn't seem an unreasonable flag to enable, but a 140x regression is too much to get developers to swallow. There are 2 performance considerations: 1) the

Re: GetPrimitiveArrayCritical vs GetByteArrayRegion: 140x slow-down using -Xcheck:jni and java.util.zip.DeflaterOutputStream

On 05/03/2018 06:33, David Holmes wrote: Hi Ian, Do you run with -Xcheck:jni in production mode because you load unknown native code libraries? It's mainly intended as a diagnostic option to turn on if you encounter a possible JNI problem. It does unusual to be running with -Xcheck:jni in

Re: GetPrimitiveArrayCritical vs GetByteArrayRegion: 140x slow-down using -Xcheck:jni and java.util.zip.DeflaterOutputStream

Hi Ian, Do you run with -Xcheck:jni in production mode because you load unknown native code libraries? It's mainly intended as a diagnostic option to turn on if you encounter a possible JNI problem. I'll leave the debate on your actual patch proposal to others more familiar with the