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Crash-Only Software

45 points by llambda 15y ago

zeit_geist 15y ago
Should be part of the standard CS curriculum.
Yoric 15y ago
Definitely interesting for anyone who's into Operating Systems and/or distributed programming.
lukego 15y ago
I really enjoyed one of this paper's citations, "Why do computers stop and what can be done about it" written by Jim Gray in 1985. A really nice and early look at how to build reliable systems from unreliable but independent parts. http://www.hpl.hp.com/techreports/tandem/TR-85.7.html http://www.hpl.hp.com/techreports/tandem/TR-85.7.html
jchrisa 15y ago
This is one Damien Katz sites as a big influence on the CouchDB design.
nandemo 15y ago
Is Firefox crash-only? When I have to restart my system, I just do it without closing the browser. After the system reboots, I launch Firefox and it brings all the windows and tabs back. (I don't know if there's a cleaner way to do that, without manually saving all the tabs in every window)
- justincormack 15y ago
  There is a quit option in the menu, so no. I think it can be configured to restore state on a clean exit. Chrome can.
- cdr 15y ago
  If the default behavior isn't working for you, give the Session Manager add-on a try.
cpeterso 15y ago
What would be necessary to adapt a Linux distro to be crash-only? shutdown now really would mean shutdown now. Unfortunately, I doubt many Linux services or applications would be happy if there shutdown scripts did not run. If the distro can't be made crash-only, perhaps just the Linux kernel could. After executing shutdown scripts for userspace services, just crash the kernel. Good tests for filesystems and device drivers! :)
- justincormack 15y ago
  You can work towards making userspace crash only. Generally you want to make it stateless as much as possible, ie avoid writing to lots of files, only config databases that are crash proof. A few people have been looking at stateless userspace eg see http://www.infoq.com/presentations/Runtime-Changes http://www.infoq.com/presentations/Runtime-Changes Current Linux distros generally have too much poorly documented state in the filesystem, much of which may not be updated in a crash proof way...
- forgotusername 15y ago
  The kernel (along with a modern FS) already is crash-only. Journals are designed to recover a FS quickly from any state after a power failure. The remainder of the kernel mostly is a bunch of in-memory structures recreated on every boot. As for userspace, well, e.g. Firefox is a lot of the way there. SQLite itself is designed to handle failures extremely gracefully, and by virtue of regularly flushing most of its state into SQLite, Firefox itself achieves a great deal of reliability (although this might not be true of its cache storage, etc.).
- X-Istence 15y ago
  Mac OS X has already provided a lot of the framework for applications, it is opt-in for app developers, but it allows for an app to be kill -9'ed on shutdown. Definitely take a look at Sudden Termination as Apple calls it. It is one of the few features along with restoring apps as they were upon login means that a reboot is no longer a productivity killer.
Vitaly 15y ago
Very good stuff. I was first exposed to it by the design of Cassandra which works exactly like that. To stop it you just ceash it and it always start with recovery.
wnoise 15y ago
See also Erlang, where one commonly encouraged way of handling errors is to crash a process, and let another process restart it.
- Yoric 15y ago
  Erlang is "let it crash", which is not exactly the same thing, but it's quite close, and just as interesting.
mad44 15y ago
Here is a short summary of the paper. http://muratbuffalo.blogspot.com/2011/01/crash-only-software-hotos03.html http://muratbuffalo.blogspot.com/2011/01/crash-only-software...

Crash-Only Software

45 points by llambda 15y ago

zeit_geist 15y ago

Should be part of the standard CS curriculum.

Yoric 15y ago

Definitely interesting for anyone who's into Operating Systems and/or distributed programming.

lukego 15y ago

I really enjoyed one of this paper's citations, "Why do computers stop and what can be done about it" written by Jim Gray in 1985. A really nice and early look at how to build reliable systems from unreliable but independent parts. http://www.hpl.hp.com/techreports/tandem/TR-85.7.html http://www.hpl.hp.com/techreports/tandem/TR-85.7.html

jchrisa 15y ago

This is one Damien Katz sites as a big influence on the CouchDB design.

nandemo 15y ago

Is Firefox crash-only? When I have to restart my system, I just do it without closing the browser. After the system reboots, I launch Firefox and it brings all the windows and tabs back. (I don't know if there's a cleaner way to do that, without manually saving all the tabs in every window)

justincormack 15y ago
There is a quit option in the menu, so no. I think it can be configured to restore state on a clean exit. Chrome can.
cdr 15y ago
If the default behavior isn't working for you, give the Session Manager add-on a try.

cpeterso 15y ago

What would be necessary to adapt a Linux distro to be crash-only? shutdown now really would mean shutdown now. Unfortunately, I doubt many Linux services or applications would be happy if there shutdown scripts did not run. If the distro can't be made crash-only, perhaps just the Linux kernel could. After executing shutdown scripts for userspace services, just crash the kernel. Good tests for filesystems and device drivers! :)

justincormack 15y ago
You can work towards making userspace crash only. Generally you want to make it stateless as much as possible, ie avoid writing to lots of files, only config databases that are crash proof. A few people have been looking at stateless userspace eg see http://www.infoq.com/presentations/Runtime-Changes http://www.infoq.com/presentations/Runtime-Changes Current Linux distros generally have too much poorly documented state in the filesystem, much of which may not be updated in a crash proof way...
forgotusername 15y ago
The kernel (along with a modern FS) already is crash-only. Journals are designed to recover a FS quickly from any state after a power failure. The remainder of the kernel mostly is a bunch of in-memory structures recreated on every boot. As for userspace, well, e.g. Firefox is a lot of the way there. SQLite itself is designed to handle failures extremely gracefully, and by virtue of regularly flushing most of its state into SQLite, Firefox itself achieves a great deal of reliability (although this might not be true of its cache storage, etc.).
X-Istence 15y ago
Mac OS X has already provided a lot of the framework for applications, it is opt-in for app developers, but it allows for an app to be kill -9'ed on shutdown. Definitely take a look at Sudden Termination as Apple calls it. It is one of the few features along with restoring apps as they were upon login means that a reboot is no longer a productivity killer.

Vitaly 15y ago

Very good stuff. I was first exposed to it by the design of Cassandra which works exactly like that. To stop it you just ceash it and it always start with recovery.

wnoise 15y ago

See also Erlang, where one commonly encouraged way of handling errors is to crash a process, and let another process restart it.

Yoric 15y ago
Erlang is "let it crash", which is not exactly the same thing, but it's quite close, and just as interesting.

mad44 15y ago

Here is a short summary of the paper. http://muratbuffalo.blogspot.com/2011/01/crash-only-software-hotos03.html http://muratbuffalo.blogspot.com/2011/01/crash-only-software...