David, is what is said about memory management really true? I thought that saving the image triggered a garbage collect what forces to copy the whole memory anyway. Lukas On 23 July 2010 14:00, David T. Lewis <lewis@mail.msen.com> wrote:
On Fri, Jul 23, 2010 at 09:49:46AM +0200, Lukas Renggli wrote:
But How I can do that without fork? I track changes in another process and when I do update I save image in this process. How I can initiate image saving from ui process?
I don't understand what you are saying.
The thing is that using #fork to save the image has no effect (other than wrecking the image), because #snapshot:andQuit: is eventually calling a primitive that locks the complete VM anyway.
If you want to fork while saving the image you need to use an OS-level fork, not a Smalltalk-level fork. You can do this with OSProcess for example (check the Seaside mailing-list archive).
"UnixProcess saveImageInBackgroundNicely"
Explained in the method comment:
UnixProcess class>>saveImageInBackground: savedImageName nice: niceFlag     "When Squeak is used as a server it is sometimes desirable to periodically     save image snapshots. This method forks a headless Squeak to perform a     snapshot without impacting the server Squeak. Very little additional memory     is required to do this because Unix copy-on-write memory management allows     the two Squeak images to share object memory while the save is performed.     The saved image is given a time stamped name, and the image name of     the main server Squeak remains unchanged. If niceFlag is true, the     background OS process runs at lowered scheduling priority."
Dave
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