On 20/05/2021 6:25 pm, Colin Paice wrote:
Are there any magic options to say "load a jar - just once ... not once
for each thread", or to tell Java to load from the shared classes cache?
It feels like an old (non java) problem of having a non reentrant load
module, so it was loaded from disk
Timothy,
Thanks for these links. Are these fixes available in the ACDC downloads?
I was told that shared classes should make startup faster. I've been
playing with it and have noticed a few interesting things.
1. I think the default shared classes cache size is 60MB... Ive made it
100MB
If you're experiencing long z/OS Management Facility startup times then
please check that you have installed the PTFs for several APARs. You might
consider disabling the z/OSMF help feature (if you can safely live without
it) since it represents a substantial fraction of startup time/energy.
On 19/05/2021 3:46 pm, Andrew Rowley wrote:
On 19/05/2021 12:27 pm, David Crayford wrote:
Then why not write your product in C++? It would be a lot easier to
process SMF records using structs then having to write get methods in
Java. Contrary to what some people believe C++ is a very modern
On 19/05/2021 12:27 pm, David Crayford wrote:
Then why not write your product in C++? It would be a lot easier to
process SMF records using structs then having to write get methods in
Java. Contrary to what some people believe C++ is a very modern
language with the benefit that it's not
On 19/05/2021 8:14 am, Andrew Rowley wrote:
That's unfortunate. It's the same where I work. We run a enterprise
class z15 and the zIIP normalized times in the SMF30s match GCP
times. What you really want is an image where you can compare code
running on a zIIP to a sub-capacity GCP
as that's
On 18/05/2021 9:21 pm, David Crayford wrote:
That's unfortunate. It's the same where I work. We run a enterprise
class z15 and the zIIP normalized times in the SMF30s match GCP times.
What you really want is an image where you can compare code running on
a zIIP to a sub-capacity GCP
as that's
On Fri, 14 May 2021 13:03:17 -0400, Matt Hogstrom wrote:
>It takes z/OSMF about an hour to fully initialize on my ZD … same behavior
>(lots of SIOs and CPU) IBM says its fixing this but its been quite a while.
>Its Java related.
>
>Matt Hogstrom
>m...@hogstrom.org
Wow, that's a long time. I
Discussion List [IBM-MAIN@LISTSERV.UA.EDU] on behalf of
David Crayford [dcrayf...@gmail.com]
Sent: Tuesday, May 18, 2021 5:12 AM
To: IBM-MAIN@LISTSERV.UA.EDU
Subject: Re: How can I tell the zFS files being used by my application
On 18/05/2021 1:52 am, Kirk Wolf wrote:
>
> - good low-overhead (sa
On 18/05/2021 6:35 pm, Andrew Rowley wrote:
On 18/05/2021 5:21 pm, David Crayford wrote:
Do they have a zIIP on the RDP system?
Yes, although the regular CPs are the same speed. Having the zIIP
means I can get figures for zIIP, CP and zIIP on CP.
That's unfortunate. It's the same where I
On 18/05/2021 5:21 pm, David Crayford wrote:
Do they have a zIIP on the RDP system?
Yes, although the regular CPs are the same speed. Having the zIIP means
I can get figures for zIIP, CP and zIIP on CP.
Are you talking about CMF 110 records? If so we've both worked on
similar stuff. One of
Sorry about the typos. OpenJDK Flight Record was GA from Java 9 onwards.
So fingers crossed we will see that when the Java 11 is finally
available on z/OS.
On 18/05/2021 5:12 pm, David Crayford wrote:
Unfortunately, othing has changed :( z/OS only partially supports the
JVMTI implementation.
On 18/05/2021 1:52 am, Kirk Wolf wrote:
- good low-overhead (sampling) profiling tools for the z/OS JVM don't
exist (maybe this has changed?). IMO this was a huge barrier for
Java on z/OS.
Unfortunately, othing has changed :( z/OS only partially supports the
JVMTI implementation.
On 18/05/2021 1:32 pm, Andrew Rowley wrote:
On 16/05/2021 12:59 pm, David Crayford wrote:
And there is a good chance that you could introduce unacceptable
software charges. I've worked on performance reporting tools for over
two decades and in my experience customers measure everything, as
On 15/05/2021 3:03 am, Matt Hogstrom wrote:
It takes z/OSMF about an hour to fully initialize on my ZD … same behavior
(lots of SIOs and CPU) IBM says its fixing this but its been quite a while. Its
Java related.
I did some investigation a while back using type 92 SMF records to try
to
On 16/05/2021 12:59 pm, David Crayford wrote:
And there is a good chance that you could introduce unacceptable
software charges. I've worked on performance reporting tools for over
two decades and in my experience customers measure everything, as any
spike in workload can be a disaster in
SMF 92 subtype 11 is usually useful in showing USS file activity, which can
tend to reveal if anything 'odd' is going on with file based activity.
I/O is also seen when network activity is involved, but I have not found
92's very useful in determining what is going on in that arena, but others
may
On 18/05/2021 2:05 am, Kirk Wolf wrote:
Sorry, I meant to add that agree with David. If you have big Java
apps that use significant CPU, you really need to run them on zIIP or
the costs will be intolerable.
In the particular case of the large Australian customer, I wonder why
they didn't
Sorry, I meant to add that agree with David. If you have big Java apps
that use significant CPU, you really need to run them on zIIP or the
costs will be intolerable.
In the particular case of the large Australian customer, I wonder why
they didn't see the issue coming early on?
Kirk Wolf
We haven't done much with Java in the last few years, but our experience
with mission-critical production Java apps on z/OS (going back almost 20
years) is a little mixed.
- JVM startup is rather expensive, especially the full JITing of classes.
- the more classes you pull in (like huge class
4) z15 System Recovery Boost (which I guess the sales folks thought
would be fun to call SRB) can use zIIP's for general CP work around IPL
time.
On 5/15/2021 6:31 PM, Andrew Rowley wrote:
On 15/05/2021 3:33 pm, David Crayford wrote:
I don't believe that is true. zIIP engines give you 3
On 16/05/2021 9:31 am, Andrew Rowley wrote:
On 15/05/2021 3:33 pm, David Crayford wrote:
Java is not viable on z/OS without zIIP engines.
I don't believe that is true. zIIP engines give you 3 things:
Answered below.
1) Savings in software cost.
Imperative. One of our customers, a
On 15/05/2021 3:33 pm, David Crayford wrote:
Java is not viable on z/OS without zIIP engines.
I don't believe that is true. zIIP engines give you 3 things:
1) Savings in software cost.
2) Full speed CPUs, if your general purpose CPs are not full speed
3) Very often, they are less utilized
On 15/05/2021 1:03 am, Matt Hogstrom wrote:
It takes z/OSMF about an hour to fully initialize on my ZD … same behavior
(lots of SIOs and CPU) IBM says its fixing this but its been quite a while. Its
Java related.
And how much does ZD cost? We had customer complain that our Apache
Tomcat
This is usually due to Websphere scanning the dropins folder for
updates. z/OS doesn't have edge triggered kernel hooks like inotify on
Linux so has to use brute force. It's not just I/O it consumes a lot of CPU.
You can disable it in server.xml
locationMonitoringEnabled="false"
Tell them what?
Chris Hoelscher
Lead Sys DBA
IBM Global Technical Services on assignmemt to Humana Inc.
T 502.476.2538 or 502.407.7266
The information transmitted is intended only for the person or entity to which
it is addressed
and may contain CONFIDENTIAL material. If you receive this
Matt,
One problem with the Slow start up is the first time it has to
compile/cache things - the second time it is faster. Ive blogged on saving
the cached stuff across restarts.
I hear one of the problems is to do with the checking access to files, not
Java as such.
Z/OSMF had been up and I had
It takes z/OSMF about an hour to fully initialize on my ZD … same behavior
(lots of SIOs and CPU) IBM says its fixing this but its been quite a while.
Its Java related.
Matt Hogstrom
m...@hogstrom.org
+1-919-656-0564
PGP Key: 0x90ECB270
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