To add a bit more data to this. I surveyed the rest of the VM Parameters. (1-25, above 25 I was getting primitive failures and I don't believe any of those are relevant, let me know if I am mistaken.) And I can't find any data there that explains the discrepancy reported between VM Parameter 3 (end of memory) and the resident set size of the process as reported by the operating system.
Ignoring those entries that are clearly counts of GC iterations and GC runtimes and such all of the rest of the values that seem like they might be related to memory usage summed up does not come close the current discrepancy of about 70MB.
I would really really appreciate some guidance here.
Ken
On Fri, 2010-10-15 at 15:05 -0500, Ken Causey wrote:
On Thu, 2010-10-14 at 19:00 -0700, Ken Causey wrote:
-------- Original Message -------- Subject: Re: [Webteam] Re: [squeak-dev] What are we leaking in the www.squeak.org process? From: Igor Stasenko siguctua@gmail.com Date: Thu, October 14, 2010 8:45 pm To: The general-purpose Squeak developers list squeak-dev@lists.squeakfoundation.org
On 15 October 2010 04:10, Ken Causey ken@kencausey.com wrote:
Another update with more data conflicting somewhat with my last report:
Shown by ps: 214560KB RSS Shown by vmParameters (2,3): 64.6MB/67.4MB
A discrepancy of some 150MB.
My understanding is, that Squeak VM cannot shrink a memory which were commited (due to peak growth), to give it back to OS.
So, if at some peak, VM comitted 150 MB, and OS sees it as 150M, while VM after GC actually using just 64M.
No, I don't believe this is true. The RSS does go both down as well as up. I thought I made that clear in my original comments.
Although I suppose it is possible that drops in the RSS figure are due to paging out to swap. I'm not sure how to really check that.
Ken
For example, another data point:
Shown by ps: 167344KB RSS Shown by vmParameters (2,3): 62.9MB/65.8MB
The process has not been restarted but the RSS has dropped.
Ken
Ken
On Thu, 2010-10-14 at 17:31 -0500, Ken Causey wrote:
An update as things may not be quite as I originally described them. It seems the values reported by vmParameters 2 and 3 are not as constant as I had been lead to believe. I noticed that just a short while after sending the image the RSS had jumped up to 165800KB. I still had VNC open on the image so I checked what is shown there and I see 145.6MB/147.7MB so there is still a discrepancy, but not perhaps as wide as I indicated.
I also did not mention that in addition to restarting Swazoo every 15 minutes there is other cleanup that is done once a day related to statistics gathering that goes on. My understanding is that this cleanup is meant to return things very close to the starting state. Perhaps Janko can comment on that more fully.
Ken
On Thu, 2010-10-14 at 16:55 -0500, Ken Causey wrote:
For some time now I've been bugging Janko about the memory usage of the process that serves http://www.squeak.org/ . I've gathered a bit more info today and I'd like to see if anyone here has any thoughts.
First while there is some variation most of the Squeak processes that serve squeak.org sites (source.squeak.org, map.squeak.org, wiki.squeak.org) have a more or less constant and reasonable memory usage. Let me clarify that what I am talking about here is RSS (Resident Set Size) as reported by ps/top on Linux. Swiki as the oldest of the group is the clear winner at just under 30MB, squeakmap is around 47MB, and source.squeak.org is around 59MB.
In contrast immediately after starting it www.squeak.org is using about 70MB and it grows from there. Now a bit more than an hour since the last restart it is already up to about 85MB. I have seen it over 300MB before, and it commonly uses 140-250MB. It doesn't simply grow and grow, it does shrink occasionally.
First, there is a known issue with Swazoo that it does not close sockets correctly and Janko has addressed this by having Swazoo automatically restarted every 15 minutes. So using netstat for example I can watch the socket count for the process continually grow and then it drops to zero and this repeats. In contrast for all the other process (all running some variation of Kom/Comanche I believe) I'm hard pressed to even catch a single open socket at any time (not counting the listener that is).
Secondly, since I've been complaining about this issue for a long time Janko has running a little morph that shows current memory usage. What this shows is the values of SmalltalkImage current vmParameterAt: 2 and 3. These numbers are quite stable. For example at this moment these are 68.3MB and 71.0MB respectively. Whereas ps shows the RSS at 85752KB. Where is the discrepancy here?
My current theory is that the vmParameters are not reflecting incidental memory use by the VM and plugins or that we are simply misinterpreting the values. Is it possible that Swazoo is failing to release something that is causing the VM to use more memory than it should?
Note that the same VM is used by all of these processes. It is
3.8a-1 #1 Sun May 1 19:46:46 EDT 2005 gcc 3.3.5
Yes, I know it's old, but 'if it ain't broke, don't fix it' has been the motto and with the possible exception of Swazoo/www.squeak.org it has been working wonderfully for a long time now.
Your thoughts would be greatly appreciated,
Ken
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-- Best regards, Igor Stasenko AKA sig.
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