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[Ann] Checkpointing Ruby applications (DragonFlyBSD only

Michael Neumann

11/24/2004 12:54:00 AM

Hi,

With DragonFlyBSD (www.dragonflybsd.org) it's now possible to checkpoint
processes. That means, that you can store a dump of the running
application to disk, from which you can resume later on (possibly on
another machine). I mention this, because it's especially interesting
for Web frameworks like Wee or Borges, which use Continuations and
Threads, that are not marshallable (but checkpointable ;-).

I've made a Ruby module around the sys_checkpoint syscall. You can find
the module here:

http://www.ntecs.de/viewcvs/viewcvs/DragonFly/c...

Of course, you have to restore sockets, pipes etc. on resume yourself.

Regards,

Michael
7 Answers

Michael Neumann

11/24/2004 1:00:00 AM

0

Michael Neumann wrote:
> Hi,
>
> With DragonFlyBSD (www.dragonflybsd.org) it's now possible to checkpoint
> processes. That means, that you can store a dump of the running
> application to disk, from which you can resume later on (possibly on
> another machine). I mention this, because it's especially interesting
> for Web frameworks like Wee or Borges, which use Continuations and
> Threads, that are not marshallable (but checkpointable ;-).
>
> I've made a Ruby module around the sys_checkpoint syscall. You can find
> the module here:
>
> http://www.ntecs.de/viewcvs/viewcvs/DragonFly/c...
>
> Of course, you have to restore sockets, pipes etc. on resume yourself.

Maybe I'll give a simple example:

require 'checkpoint'
Checkpoint.checkpoint('dump')
p '.'
Checkpoint.resume('dump')

This will loop infinite and print '.' on the screen.
Or this one:

$conn = TCPServer....

Checkpoint.checkpoint('dump') do
# setup sockets on resume
$conn = TCPServer.open('localhost', 9999)
end

....

If you resume from "dump" (type 'checkpt -r dump' on command line, or
'ruby -r checkpoint -e 'Checkpoint.resume("dump")'), the block will be
executed.

Regards,

Michael

David Ross

11/24/2004 2:24:00 AM

0

Michael Neumann wrote:

> Hi,
>
> With DragonFlyBSD (www.dragonflybsd.org) it's now possible to
> checkpoint processes. That means, that you can store a dump of the
> running application to disk, from which you can resume later on
> (possibly on another machine). I mention this, because it's especially
> interesting for Web frameworks like Wee or Borges, which use
> Continuations and Threads, that are not marshallable (but
> checkpointable ;-).
>
> I've made a Ruby module around the sys_checkpoint syscall. You can
> find the module here:
>
> http://www.ntecs.de/viewcvs/viewcvs/DragonFly/c...
>
> Of course, you have to restore sockets, pipes etc. on resume yourself.
>
> Regards,
>
> Michael
>
>
>
>
I'm glad there are others who appreciate BSDs. What made you interested?

David Ross
--
Hazzle free packages for Ruby?
RPA is available from http://www.rubyar...

Lothar Scholz

11/24/2004 2:39:00 AM

0

Hello Michael,

MN> Checkpoint.checkpoint('dump') do
MN> # setup sockets on resume
MN> $conn = TCPServer.open('localhost', 9999)
MN> end

MN> If you resume from "dump" (type 'checkpt -r dump' on command line, or
MN> 'ruby -r checkpoint -e 'Checkpoint.resume("dump")'), the block will be
MN> executed.

Did you any measurements how much time is saved for startup of a
complexer ruby program with lots of requires ? Something like
FreeRide would be nice. I don't have BSD installed so i can't do it myself.

Also why isn't it possible to directly run the checkpoint file from
the shell ?


--
Best regards, emailto: scholz at scriptolutions dot com
Lothar Scholz http://www.ru...
CTO Scriptolutions Ruby, PHP, Python IDE 's

Michael Neumann

11/24/2004 10:58:00 AM

0

Lothar Scholz wrote:
> Hello Michael,
>
> MN> Checkpoint.checkpoint('dump') do
> MN> # setup sockets on resume
> MN> $conn = TCPServer.open('localhost', 9999)
> MN> end
>
> MN> If you resume from "dump" (type 'checkpt -r dump' on command line, or
> MN> 'ruby -r checkpoint -e 'Checkpoint.resume("dump")'), the block will be
> MN> executed.
>
> Did you any measurements how much time is saved for startup of a
> complexer ruby program with lots of requires ? Something like
> FreeRide would be nice. I don't have BSD installed so i can't do it myself.

Not yet. I never had timing problems with lots of requires...
If I can compile freeride (FX...) easily I'll report my results.

> Also why isn't it possible to directly run the checkpoint file from
> the shell ?

It is possible:

checkpt -r checkpoint-file

Well, it's in reality a core-dump (or so I'm told), and it has to be
sent the CKPTEXIT signal, so that it can perform some setup-tasks... and
it will return from the sys_checkpoint syscall with a given value. Not
sure how this all could be done easily with a directly executable file,
without modifying the core-dump to much.

Regards,

Michael

Michael Neumann

11/24/2004 11:06:00 AM

0

David Ross wrote:
> Michael Neumann wrote:
>
>> Hi,
>>
>> With DragonFlyBSD (www.dragonflybsd.org) it's now possible to
>> checkpoint processes. That means, that you can store a dump of the
>> running application to disk, from which you can resume later on
>> (possibly on another machine). I mention this, because it's especially
>> interesting for Web frameworks like Wee or Borges, which use
>> Continuations and Threads, that are not marshallable (but
>> checkpointable ;-).
>>
>> I've made a Ruby module around the sys_checkpoint syscall. You can
>> find the module here:
>>
>> http://www.ntecs.de/viewcvs/viewcvs/DragonFly/c...
>>
>> Of course, you have to restore sockets, pipes etc. on resume yourself.
>>
>> Regards,
>>
>> Michael
>>
>>
>>
>>
> I'm glad there are others who appreciate BSDs. What made you interested?

In BSD in general or in DragonFly? Well, with DragonFly it's a bit like
with Ruby. You can get easily responses from it's creator (indeed, it's
easier to get a response from Matt than from Matz ;-), and problems are
solved mostly very quickly. You know where to asks, community is small
and friendly.

But most importantly, I dropped FreeBSD 5.3, as it paniced on Monday 3
times in a row (maybe it's not FreeBSD's fault, but *I* encountered a
lot of crashes in the 5.x line). Now, I'll count every crashes of
DragonFly. Zero up to now ;-)

And of course the ideas behind DragonFly are IMHO superior. I am happy
each time when Matt has removed a lot of code (rewrote it) or made the
API much simpler.

Regards,

Michael

Michael Neumann

11/24/2004 11:43:00 AM

0

Michael Neumann wrote:
> Lothar Scholz wrote:
>
>> Hello Michael,
>>
>> MN> Checkpoint.checkpoint('dump') do
>> MN> # setup sockets on resume
>> MN> $conn = TCPServer.open('localhost', 9999)
>> MN> end
>>
>> MN> If you resume from "dump" (type 'checkpt -r dump' on command line, or
>> MN> 'ruby -r checkpoint -e 'Checkpoint.resume("dump")'), the block
>> will be
>> MN> executed.
>>
>> Did you any measurements how much time is saved for startup of a
>> complexer ruby program with lots of requires ? Something like
>> FreeRide would be nice. I don't have BSD installed so i can't do it
>> myself.
>
>
> Not yet. I never had timing problems with lots of requires...
> If I can compile freeride (FX...) easily I'll report my results.

It's not possible to restore freeride (or any GUI programm, I guess), as
X11 is involved... Sockets!

Regards,

Michael

Lothar Scholz

11/24/2004 12:23:00 PM

0

Hello Michael,

MN> Michael Neumann wrote:
>> Lothar Scholz wrote:
>>
>>> Hello Michael,
>>>
>>> MN> Checkpoint.checkpoint('dump') do
>>> MN> # setup sockets on resume
>>> MN> $conn = TCPServer.open('localhost', 9999)
>>> MN> end
>>>
>>> MN> If you resume from "dump" (type 'checkpt -r dump' on command line, or
>>> MN> 'ruby -r checkpoint -e 'Checkpoint.resume("dump")'), the block
>>> will be
>>> MN> executed.
>>>
>>> Did you any measurements how much time is saved for startup of a
>>> complexer ruby program with lots of requires ? Something like
>>> FreeRide would be nice. I don't have BSD installed so i can't do it
>>> myself.
>>
>>
>> Not yet. I never had timing problems with lots of requires...
>> If I can compile freeride (FX...) easily I'll report my results.

MN> It's not possible to restore freeride (or any GUI programm, I guess), as
MN> X11 is involved... Sockets!

Right, but you can set a checkpoint before connecting to X11.

Could be nice for large, commercial software. Startup time when you
require hundred thousand lines ruby code is not really funny.

Lisp/Smalltalk users know what i'm talking about.


--
Best regards, emailto: scholz at scriptolutions dot com
Lothar Scholz http://www.ru...
CTO Scriptolutions Ruby, PHP, Python IDE 's