Hi Lennart, I can reproduce this locally, and have narrowed down to https://bugs.openjdk.java.net/browse/JDK-8034802 as the cause. As you say the compression is deferred to ZipFileSystem.close() now, whereas previously it happened eagerly. We will have to analyze the changes more in-depth to try and see why this is the case. Thanks! /Claes On 2019-04-15 15:32, Lennart Börjeson wrote:

I have made a small command-line utility which creates zip archives by compressing the input files in parallel.

I do this by calling Files.copy(input, zipOutputStream) in a parallel Stream over all input files.

I have run this with Java 1.8, 9, 10, and 11, on both my local laptop and on server-class machines with up to 40 cores.

It scales rather well and I get the expected speedup, i.e. roughly proportional to the number of cores.

With OpenJDK 12, however, I get no speedup whatsoever. My understanding is that in JDK 12, the copy method simply transfers the contents of the input stream to a ByteArrayOutputStream, which is then deflated when I close the ZipFileSystem (by the ZipFileSystem.sync() method).

Previously, the deflation was done when in the call to Files.copy, thus executed in parallel, and the final ZipFileSystem.close() didn't do anything much.

(But I may of course be wrong. In case there's a simpler explanation and something I can remedy in my code, please let me know.)

I have a small GitHub gist for the utility here: https://gist.github.com/lenborje/6d2f92430abe4ba881e3c5ff83736923 <https://gist.github.com/lenborje/6d2f92430abe4ba881e3c5ff83736923>

Steps to reproduce (timings on my 8-core MacBook Pro):

1) Get the contents of the gist as a single file, Zip.java 2) Compile it using Java 8.

$ export JAVA_HOME=<PATH-TO-JDK8-HOME> $ javac -encoding utf8 Zip.java

3) run on a sufficiently large number of files to exercise the parallelity: (I've used about 70 text files ca 60MB each)

$ time java -Xmx6g Zip -p /tmp/test.zip <WHATEVER>/*.log. Working on ZIP FileSystem jar:file:/tmp/test.zip, using the options [PARALLEL] ... completed zip archive, now closing... done!

real 0m35.558s user 3m58.134s sys 0m5.543s

As is evident from the ratio between "user time" and "real time", all cores have been busy most of the time.

(Running with JDK 9, 10, and 11 produces similar timings.)

But running with JDK 12 defeats the parallelism:

$ export JAVA_HOME=<PATH-TO-JDK12-HOME> $ rm /tmp/test.zip # From previous run $ time java -Xmx6g Zip -p /tmp/test.zip <WHATEVER>/*.log. Working on ZIP FileSystem jar:file:/tmp/test.zip, using the options [PARALLEL] ... completed zip archive, now closing... done!

real 3m1.187s user 3m5.422s sys 0m12.396s

Now there's almost no speedup. When observing the output, note that the ZipFileSystem.close() method is called immediately after the "now closing..." output, and "Done!" Is written when it returns, and when running with JDK 12 almost all running time is apparently spent there.

I'm hoping the previous behaviour could somehow be restored, i.e. that deflation actually happens when I'm copying the input files to the ZipFileSystem, and not when I close it.

Best regards,

/Lennart Börjeson

...

12 apr. 2019 kl. 14:25 skrev Lennart Börjeson <lenborje@gmail.com>:

I've found what I believe is a rather severe performance regression in ZipFileSystem. 1.8 and 11 runs OK, 12 does not.

Is this the right forum to report such issues?

Best regards,

/Lennart Börjeson

Hi Claes, will you open a bug for this? Thanks Christoph

-----Original Message----- From: core-libs-dev <core-libs-dev-bounces@openjdk.java.net> On Behalf Of Lennart Börjeson Sent: Dienstag, 16. April 2019 09:05 To: Claes Redestad <claes.redestad@oracle.com> Cc: core-libs-dev@openjdk.java.net Subject: Re: ZipFileSystem performance regression

Very good, thank you!

Also note that the "new" implementation also requires *a lot* more heap, since all *uncompressed* file content is copied to the heap before deflating.

Best regards,

/Lennart Börjeson

...

15 apr. 2019 kl. 18:34 skrev Claes Redestad <claes.redestad@oracle.com>:

Hi Lennart,

I can reproduce this locally, and have narrowed down to https://bugs.openjdk.java.net/browse/JDK-8034802 as the cause.

As you say the compression is deferred to ZipFileSystem.close() now, whereas previously it happened eagerly. We will have to analyze the changes more in-depth to try and see why this is the case.

Thanks!

/Claes

On 2019-04-15 15:32, Lennart Börjeson wrote:

...

I have made a small command-line utility which creates zip archives by compressing the input files in parallel. I do this by calling Files.copy(input, zipOutputStream) in a parallel Stream over all input files. I have run this with Java 1.8, 9, 10, and 11, on both my local laptop and on server-class machines with up to 40 cores. It scales rather well and I get the expected speedup, i.e. roughly proportional to the number of cores. With OpenJDK 12, however, I get no speedup whatsoever. My understanding is that in JDK 12, the copy method simply transfers the contents of the input stream to a ByteArrayOutputStream, which is then deflated when I close the ZipFileSystem (by the ZipFileSystem.sync() method). Previously, the deflation was done when in the call to Files.copy, thus executed in parallel, and the final ZipFileSystem.close() didn't do anything much. (But I may of course be wrong. In case there's a simpler explanation and something I can remedy in my code, please let me know.) I have a small GitHub gist for the utility here: https://gist.github.com/lenborje/6d2f92430abe4ba881e3c5ff83736923 <https://gist.github.com/lenborje/6d2f92430abe4ba881e3c5ff83736923> Steps to reproduce (timings on my 8-core MacBook Pro): 1) Get the contents of the gist as a single file, Zip.java 2) Compile it using Java 8. $ export JAVA_HOME=<PATH-TO-JDK8-HOME> $ javac -encoding utf8 Zip.java 3) run on a sufficiently large number of files to exercise the parallelity: (I've used about 70 text files ca 60MB each) $ time java -Xmx6g Zip -p /tmp/test.zip <WHATEVER>/*.log. Working on ZIP FileSystem jar:file:/tmp/test.zip, using the options [PARALLEL] ... completed zip archive, now closing... done! real 0m35.558s user 3m58.134s sys 0m5.543s As is evident from the ratio between "user time" and "real time", all cores have been busy most of the time. (Running with JDK 9, 10, and 11 produces similar timings.) But running with JDK 12 defeats the parallelism: $ export JAVA_HOME=<PATH-TO-JDK12-HOME> $ rm /tmp/test.zip # From previous run $ time java -Xmx6g Zip -p /tmp/test.zip <WHATEVER>/*.log. Working on ZIP FileSystem jar:file:/tmp/test.zip, using the options [PARALLEL] ... completed zip archive, now closing... done! real 3m1.187s user 3m5.422s sys 0m12.396s Now there's almost no speedup. When observing the output, note that the ZipFileSystem.close() method is called immediately after the "now closing..." output, and "Done!" Is written when it returns, and when running with JDK 12 almost all running time is apparently spent there. I'm hoping the previous behaviour could somehow be restored, i.e. that deflation actually happens when I'm copying the input files to the ZipFileSystem, and not when I close it. Best regards, /Lennart Börjeson

...

12 apr. 2019 kl. 14:25 skrev Lennart Börjeson <lenborje@gmail.com>:

I've found what I believe is a rather severe performance regression in ZipFileSystem. 1.8 and 11 runs OK, 12 does not.

Is this the right forum to report such issues?

Best regards,

/Lennart Börjeson

Both before and after this regression, it seems the default behavior is not to use a temporary file (until ZFS.sync(), which writes to a temp file and then moves it in place, but that's different from what happens with the useTempFile option enabled). Instead entries (and the backing zip file system) are kept in-memory. The cause of the issue here is instead that no deflation happens until sync(), even when writing to entries in-memory. Previously, the deflation happened eagerly, then the result of that was copied into the zip file during sync(). I've written a proof-of-concept patch that restores the behavior of eagerly compressing entries when the method is METHOD_DEFLATED and the target is to store byte[]s in-memory (the default scenario): http://cr.openjdk.java.net/~redestad/scratch/zfs.eager_deflation.00/ This restores performance of parallel zip to that of 11.0.2 for the default case. It still has a similar regression for the case where useTempFile is enabled, but that should be easily addressed if this looks like a way forward? (I've not yet created a bug as I got too caught up in trying to figure out what was going on here...) Thanks! /Claes On 2019-04-16 09:29, Alan Bateman wrote:

On 15/04/2019 14:32, Lennart Börjeson wrote:

...

:

Previously, the deflation was done when in the call to Files.copy, thus executed in parallel, and the final ZipFileSystem.close() didn't do anything much.

Can you submit a bug? When creating/updating a zip file with zipfs then the closing the file system creates the zip file. Someone needs to check but it may have been that the temporary files (on the file system hosting the zip file) were deflated when writing (which is surprising but may have been the case).

-Alan

One of the motivations back then is to speed up the performance of accessing those entries, means you don't have to deflate/inflate those new/updated entries during the lifetime of that zipfilesystem. Those updated entries only get compressed when go to storage. So the regression is more like a trade off of performance of different usages. (it also simplifies the logic on handing different types of entries ...) One idea I experimented long time ago for jartool is to concurrently write out entries when need compression ... it does gain some performance improvement on multi-cores, but not lots, as it ends up coming back to the main thread to write out to the underlying filesystem. -Sherman On 4/16/19 5:21 AM, Claes Redestad wrote:

Both before and after this regression, it seems the default behavior is not to use a temporary file (until ZFS.sync(), which writes to a temp file and then moves it in place, but that's different from what happens with the useTempFile option enabled). Instead entries (and the backing zip file system) are kept in-memory.

The cause of the issue here is instead that no deflation happens until sync(), even when writing to entries in-memory. Previously, the deflation happened eagerly, then the result of that was copied into the zip file during sync().

I've written a proof-of-concept patch that restores the behavior of eagerly compressing entries when the method is METHOD_DEFLATED and the target is to store byte[]s in-memory (the default scenario):

http://cr.openjdk.java.net/~redestad/scratch/zfs.eager_deflation.00/

This restores performance of parallel zip to that of 11.0.2 for the default case. It still has a similar regression for the case where useTempFile is enabled, but that should be easily addressed if this looks like a way forward?

(I've not yet created a bug as I got too caught up in trying to figure out what was going on here...)

Thanks!

/Claes

On 2019-04-16 09:29, Alan Bateman wrote:

...

On 15/04/2019 14:32, Lennart Börjeson wrote:

...

:

Previously, the deflation was done when in the call to Files.copy, thus executed in parallel, and the final ZipFileSystem.close() didn't do anything much.

Can you submit a bug? When creating/updating a zip file with zipfs then the closing the file system creates the zip file. Someone needs to check but it may have been that the temporary files (on the file system hosting the zip file) were deflated when writing (which is surprising but may have been the case).

-Alan

I think this behavior should be reverted and if the new behavior something that should be opt-in via an option, if at all. Intrusive behavior changes like this should at the very least have been signalled via a clear, standalone CSR and not buried in what looked like a bug fix. /Claes On 2019-04-16 21:54, Lennart Börjeson wrote:

I’m using the tool I wrote to compress directories with thousands of log files. The standard zip utility (as well as my utility when run with JDK 12) takes up to an hour of user time to create the archive, on our server class 40+ core servers this is reduced to 1–2 minutes.

So while I understand the motivation for the change, I don’t get why you would want to use ZipFs for what in essence is a RAM disk, *unless* you want it compressed in memory?

Oh well. Do we need a new option for this?

/Lennart Börjeson

Electrogramma ab iPhono meo missum est

...

16 apr. 2019 kl. 21:44 skrev Xueming Shen <xueming.shen@gmail.com>:

One of the motivations back then is to speed up the performance of accessing

those entries, means you don't have to deflate/inflate those new/updated entries

during the lifetime of that zipfilesystem. Those updated entries only get compressed

when go to storage. So the regression is more like a trade off of performance of

different usages. (it also simplifies the logic on handing different types of entries ...)

One idea I experimented long time ago for jartool is to concurrently write out

entries when need compression ... it does gain some performance improvement

on multi-cores, but not lots, as it ends up coming back to the main thread to

write out to the underlying filesystem.

-Sherman

...

On 4/16/19 5:21 AM, Claes Redestad wrote: Both before and after this regression, it seems the default behavior is not to use a temporary file (until ZFS.sync(), which writes to a temp file and then moves it in place, but that's different from what happens with the useTempFile option enabled). Instead entries (and the backing zip file system) are kept in-memory.

The cause of the issue here is instead that no deflation happens until sync(), even when writing to entries in-memory. Previously, the deflation happened eagerly, then the result of that was copied into the zip file during sync().

I've written a proof-of-concept patch that restores the behavior of eagerly compressing entries when the method is METHOD_DEFLATED and the target is to store byte[]s in-memory (the default scenario):

http://cr.openjdk.java.net/~redestad/scratch/zfs.eager_deflation.00/

This restores performance of parallel zip to that of 11.0.2 for the default case. It still has a similar regression for the case where useTempFile is enabled, but that should be easily addressed if this looks like a way forward?

(I've not yet created a bug as I got too caught up in trying to figure out what was going on here...)

Thanks!

/Claes

...

On 2019-04-16 09:29, Alan Bateman wrote:

...

On 15/04/2019 14:32, Lennart Börjeson wrote: :

Previously, the deflation was done when in the call to Files.copy, thus executed in parallel, and the final ZipFileSystem.close() didn't do anything much.

Can you submit a bug? When creating/updating a zip file with zipfs then the closing the file system creates the zip file. Someone needs to check but it may have been that the temporary files (on the file system hosting the zip file) were deflated when writing (which is surprising but may have been the case).

-Alan

Hi, I also think the regression should be repaired and maybe we can have an option like "lazy compress" to avoid compression on write but defer it to zipfs closing time. It should also be possible to parallelize deflation during close, shouldn't it? Best regards Christoph

-----Original Message----- From: core-libs-dev <core-libs-dev-bounces@openjdk.java.net> On Behalf Of Xueming Shen Sent: Dienstag, 16. April 2019 22:50 To: Lennart Börjeson <lenborje@gmail.com> Cc: core-libs-dev@openjdk.java.net Subject: Re: ZipFileSystem performance regression

Well, have to admitted I didn't expect your use scenario when made the change. Thought as a

filesystem runtime access performance has more weight compared to shutdown performance...

basically you are no using zipfs as a filesystem, but another jar tool that happens to have

better in/out concurrent performance. Yes, back then I was working on using zipfs as a memory

filesystem. One possible usage is that javac to use it as its filesystem (temp?) to write out compiled

class files ... so I thought I can have better performance if I can keep those classes uncompressed

until the zip/jarfs is closed and written to a "jar" file.

That said, regression is a regression, we probably want to get the performance back for your

use scenario. Just wanted to give you guys some background what happened back then.

-Sherman

On 4/16/19 12:54 PM, Lennart Börjeson wrote:

...

I’m using the tool I wrote to compress directories with thousands of log files. The standard zip utility (as well as my utility when run with JDK 12) takes up to an hour of user time to create the archive, on our server class 40+ core servers this is reduced to 1–2 minutes.

So while I understand the motivation for the change, I don’t get why you would want to use ZipFs for what in essence is a RAM disk, *unless* you want it compressed in memory?

Oh well. Do we need a new option for this?

/Lennart Börjeson

Electrogramma ab iPhono meo missum est

...

16 apr. 2019 kl. 21:44 skrev Xueming Shen <xueming.shen@gmail.com>:

One of the motivations back then is to speed up the performance of accessing

those entries, means you don't have to deflate/inflate those new/updated entries

during the lifetime of that zipfilesystem. Those updated entries only get compressed

when go to storage. So the regression is more like a trade off of performance of

different usages. (it also simplifies the logic on handing different types of entries ...)

One idea I experimented long time ago for jartool is to concurrently write out

entries when need compression ... it does gain some performance improvement

on multi-cores, but not lots, as it ends up coming back to the main thread to

write out to the underlying filesystem.

-Sherman

...

On 4/16/19 5:21 AM, Claes Redestad wrote: Both before and after this regression, it seems the default behavior is not to use a temporary file (until ZFS.sync(), which writes to a temp file and then moves it in place, but that's different from what happens with the useTempFile option enabled). Instead entries (and the backing zip file system) are kept in-memory.

The cause of the issue here is instead that no deflation happens until sync(), even when writing to entries in-memory. Previously, the deflation happened eagerly, then the result of that was copied into the zip file during sync().

I've written a proof-of-concept patch that restores the behavior of eagerly compressing entries when the method is METHOD_DEFLATED and the target is to store byte[]s in-memory (the default scenario):

http://cr.openjdk.java.net/~redestad/scratch/zfs.eager_deflation.00/

This restores performance of parallel zip to that of 11.0.2 for the default case. It still has a similar regression for the case where useTempFile is enabled, but that should be easily addressed if this looks like a way forward?

(I've not yet created a bug as I got too caught up in trying to figure out what was going on here...)

Thanks!

/Claes

...

On 2019-04-16 09:29, Alan Bateman wrote:

...

On 15/04/2019 14:32, Lennart Börjeson wrote: :

Previously, the deflation was done when in the call to Files.copy, thus executed in parallel, and the final ZipFileSystem.close() didn't do anything much.

Can you submit a bug? When creating/updating a zip file with zipfs then the closing the file system creates the zip file. Someone needs to check but it may have been that the temporary files (on the file system hosting the zip file) were deflated when writing (which is surprising but may have been the case).

-Alan

On 23/04/2019 08:19, Lennart Börjeson wrote:

Any chance we might get this repaired in time for the Java 13 ramp down?

Under discussion/review here: https://mail.openjdk.java.net/pipermail/nio-dev/2019-April/006043.html

It sounds reasonable to have that as an option, but I'd like to see it requested by some user first. And at least one (micro-)benchmark where keeping entries uncompressed in memory actually shows significant positive impact. I can see it might have the opposite effect depending on how often that memory is inflated/deflated and whether or not the inflated entries cause high enough memory pressure to make GC activity spike. javac might be one application where it could be negative as it's tuned to run with a rather small max heap and already spends significant time doing GCs. /Claes On 2019-04-16 23:20, Lance Andersen wrote:

Would it be worth adding a ZIP File System property similar to createNew which enables/disables the change that Claes has made having the default be the pre-jdk 12 functionality?

...

On Apr 16, 2019, at 4:50 PM, Xueming Shen <xueming.shen@gmail.com> wrote:

Well, have to admitted I didn't expect your use scenario when made the change. Thought as a

filesystem runtime access performance has more weight compared to shutdown performance...

basically you are no using zipfs as a filesystem, but another jar tool that happens to have

better in/out concurrent performance. Yes, back then I was working on using zipfs as a memory

filesystem. One possible usage is that javac to use it as its filesystem (temp?) to write out compiled

class files ... so I thought I can have better performance if I can keep those classes uncompressed

until the zip/jarfs is closed and written to a "jar" file.

That said, regression is a regression, we probably want to get the performance back for your

use scenario. Just wanted to give you guys some background what happened back then.

-Sherman

On 4/16/19 12:54 PM, Lennart Börjeson wrote:

...

I’m using the tool I wrote to compress directories with thousands of log files. The standard zip utility (as well as my utility when run with JDK 12) takes up to an hour of user time to create the archive, on our server class 40+ core servers this is reduced to 1–2 minutes.

So while I understand the motivation for the change, I don’t get why you would want to use ZipFs for what in essence is a RAM disk, *unless* you want it compressed in memory?

Oh well. Do we need a new option for this?

/Lennart Börjeson

Electrogramma ab iPhono meo missum est

...

16 apr. 2019 kl. 21:44 skrev Xueming Shen <xueming.shen@gmail.com>:

One of the motivations back then is to speed up the performance of accessing

those entries, means you don't have to deflate/inflate those new/updated entries

during the lifetime of that zipfilesystem. Those updated entries only get compressed

when go to storage. So the regression is more like a trade off of performance of

different usages. (it also simplifies the logic on handing different types of entries ...)

One idea I experimented long time ago for jartool is to concurrently write out

entries when need compression ... it does gain some performance improvement

on multi-cores, but not lots, as it ends up coming back to the main thread to

write out to the underlying filesystem.

-Sherman

...

On 4/16/19 5:21 AM, Claes Redestad wrote: Both before and after this regression, it seems the default behavior is not to use a temporary file (until ZFS.sync(), which writes to a temp file and then moves it in place, but that's different from what happens with the useTempFile option enabled). Instead entries (and the backing zip file system) are kept in-memory.

The cause of the issue here is instead that no deflation happens until sync(), even when writing to entries in-memory. Previously, the deflation happened eagerly, then the result of that was copied into the zip file during sync().

I've written a proof-of-concept patch that restores the behavior of eagerly compressing entries when the method is METHOD_DEFLATED and the target is to store byte[]s in-memory (the default scenario):

http://cr.openjdk.java.net/~redestad/scratch/zfs.eager_deflation.00/

This restores performance of parallel zip to that of 11.0.2 for the default case. It still has a similar regression for the case where useTempFile is enabled, but that should be easily addressed if this looks like a way forward?

(I've not yet created a bug as I got too caught up in trying to figure out what was going on here...)

Thanks!

/Claes

...

On 2019-04-16 09:29, Alan Bateman wrote: > On 15/04/2019 14:32, Lennart Börjeson wrote: > : > > Previously, the deflation was done when in the call to Files.copy, thus executed in parallel, and the final ZipFileSystem.close() didn't do anything much. > Can you submit a bug? When creating/updating a zip file with zipfs then the closing the file system creates the zip file. Someone needs to check but it may have been that the temporary files (on the file system hosting the zip file) were deflated when writing (which is surprising but may have been the case).

-Alan

<http://oracle.com/us/design/oracle-email-sig-198324.gif> <http://oracle.com/us/design/oracle-email-sig-198324.gif> <http://oracle.com/us/design/oracle-email-sig-198324.gif> <http://oracle.com/us/design/oracle-email-sig-198324.gif>Lance Andersen| Principal Member of Technical Staff | +1.781.442.2037 Oracle Java Engineering 1 Network Drive Burlington, MA 01803 Lance.Andersen@oracle.com <mailto:Lance.Andersen@oracle.com>

Hi Alan already proposed the following RFEs when NIO2 was introduced: a memory FileSystemProvider [1], and a virtual FileSystemProvider [2] With these, the javac use case could work as follows: 1) create a VirtualFileSystem, with all sources mounted under “/src”, a MemoryFileSystem mounted at “/target”, and a ZipFileSystem mounted at “/dist” 2) from then on, simply work with the VirtualFileSystem: read from /src, write compilation artifacts to /target, and finally assemble a .jar file by copying from /target to /dist I think these providers would elegantly solve most use cases. And those providers could then be enhanced with further features as desired. For example, the memory FileSystem could allow on-the-fly compression, encryption, etc. [1] https://bugs.openjdk.java.net/browse/JDK-8002315 [2] https://bugs.openjdk.java.net/browse/JDK-8002316 Kind regards Anthony ________________________________ From: core-libs-dev <core-libs-dev-bounces@openjdk.java.net> on behalf of Peter Levart <peter.levart@gmail.com> Sent: Wednesday, April 17, 2019 9:23:08 AM To: Claes Redestad; Lance Andersen; Xueming Shen Cc: core-libs-dev@openjdk.java.net Subject: Re: ZipFileSystem performance regression Just a thought... Would it be feasible to create a brand new "Generic Caching Filesystem" implementation that would delegate to another filesystem for persistent storage (be it ZipFilesystem or any other) and implement interesting caching strategies (lazy flushing, concurrent flushing, etc...) So instead of parameterizing a concrete filesystem (e.g. ZipFilesystem), the filesystems could be layered to achieve the desired performance characteristics. What do you think? Is the existing filesystem API suitable for such layering? Regards, Peter On 4/16/19 11:50 PM, Claes Redestad wrote:

It sounds reasonable to have that as an option, but I'd like to see it requested by some user first. And at least one (micro-)benchmark where keeping entries uncompressed in memory actually shows significant positive impact.

I can see it might have the opposite effect depending on how often that memory is inflated/deflated and whether or not the inflated entries cause high enough memory pressure to make GC activity spike. javac might be one application where it could be negative as it's tuned to run with a rather small max heap and already spends significant time doing GCs.

/Claes

On 2019-04-16 23:20, Lance Andersen wrote:

...

Would it be worth adding a ZIP File System property similar to createNew which enables/disables the change that Claes has made having the default be the pre-jdk 12 functionality?

...

On Apr 16, 2019, at 4:50 PM, Xueming Shen <xueming.shen@gmail.com> wrote:

Well, have to admitted I didn't expect your use scenario when made the change. Thought as a

filesystem runtime access performance has more weight compared to shutdown performance...

basically you are no using zipfs as a filesystem, but another jar tool that happens to have

better in/out concurrent performance. Yes, back then I was working on using zipfs as a memory

filesystem. One possible usage is that javac to use it as its filesystem (temp?) to write out compiled

class files ... so I thought I can have better performance if I can keep those classes uncompressed

until the zip/jarfs is closed and written to a "jar" file.

That said, regression is a regression, we probably want to get the performance back for your

use scenario. Just wanted to give you guys some background what happened back then.

-Sherman

On 4/16/19 12:54 PM, Lennart Börjeson wrote:

...

I’m using the tool I wrote to compress directories with thousands of log files. The standard zip utility (as well as my utility when run with JDK 12) takes up to an hour of user time to create the archive, on our server class 40+ core servers this is reduced to 1–2 minutes.

So while I understand the motivation for the change, I don’t get why you would want to use ZipFs for what in essence is a RAM disk, *unless* you want it compressed in memory?

Oh well. Do we need a new option for this?

/Lennart Börjeson

Electrogramma ab iPhono meo missum est

...

16 apr. 2019 kl. 21:44 skrev Xueming Shen <xueming.shen@gmail.com>:

One of the motivations back then is to speed up the performance of accessing

those entries, means you don't have to deflate/inflate those new/updated entries

during the lifetime of that zipfilesystem. Those updated entries only get compressed

when go to storage. So the regression is more like a trade off of performance of

different usages. (it also simplifies the logic on handing different types of entries ...)

One idea I experimented long time ago for jartool is to concurrently write out

entries when need compression ... it does gain some performance improvement

on multi-cores, but not lots, as it ends up coming back to the main thread to

write out to the underlying filesystem.

-Sherman

...

On 4/16/19 5:21 AM, Claes Redestad wrote: Both before and after this regression, it seems the default behavior is not to use a temporary file (until ZFS.sync(), which writes to a temp file and then moves it in place, but that's different from what happens with the useTempFile option enabled). Instead entries (and the backing zip file system) are kept in-memory.

The cause of the issue here is instead that no deflation happens until sync(), even when writing to entries in-memory. Previously, the deflation happened eagerly, then the result of that was copied into the zip file during sync().

I've written a proof-of-concept patch that restores the behavior of eagerly compressing entries when the method is METHOD_DEFLATED and the target is to store byte[]s in-memory (the default scenario):

http://cr.openjdk.java.net/~redestad/scratch/zfs.eager_deflation.00/

This restores performance of parallel zip to that of 11.0.2 for the default case. It still has a similar regression for the case where useTempFile is enabled, but that should be easily addressed if this looks like a way forward?

(I've not yet created a bug as I got too caught up in trying to figure out what was going on here...)

Thanks!

/Claes

> On 2019-04-16 09:29, Alan Bateman wrote: >> On 15/04/2019 14:32, Lennart Börjeson wrote: >> : >> >> Previously, the deflation was done when in the call to >> Files.copy, thus executed in parallel, and the final >> ZipFileSystem.close() didn't do anything much. >> > Can you submit a bug? When creating/updating a zip file with > zipfs then the closing the file system creates the zip file. > Someone needs to check but it may have been that the temporary > files (on the file system hosting the zip file) were deflated > when writing (which is surprising but may have been the case). > > -Alan

<http://oracle.com/us/design/oracle-email-sig-198324.gif> <http://oracle.com/us/design/oracle-email-sig-198324.gif> <http://oracle.com/us/design/oracle-email-sig-198324.gif> <http://oracle.com/us/design/oracle-email-sig-198324.gif>Lance Andersen| Principal Member of Technical Staff | +1.781.442.2037 Oracle Java Engineering 1 Network Drive Burlington, MA 01803 Lance.Andersen@oracle.com <mailto:Lance.Andersen@oracle.com>