# Accessing ruby objects across VMs **URL:** \ **Category:** Ruby\ **Created:** [April 21, 2009, 12:14am UTC](https://www.ruby-forum.com/t/accessing-ruby-objects-across-vms/166008 "2009-04-21T00:14:13Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![piyush\_r](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/73ab20/32.png) [@piyush\_r](https://www.ruby-forum.com/u/piyush_r)\ **Post date:** [April 21, 2009, 12:14am UTC](https://www.ruby-forum.com/t/accessing-ruby-objects-across-vms/166008/1 "2009-04-21T00:14:13Z")
I have 1 ruby instance running for a website. I do heavy polling using in memory data and to do run a few more. I have all my data stored in a MySQL DB. Right now whenever an entry is made to this DB (containing only a single table), I cache this data in memory and that serves my purpose. Now as the traffic is increasing I need to start more ruby instances. Is there any way to store this data in a single in-memory location and access it from all other vms ? There are a few options that come to my mind like 1. Storing in a memcache 2. Storing in localmemcache The problem with both of these options is that I need to store heavily nested objects. If I do that in memcache I may have to do using something like Marshal dump and load which is a little slow for my liking. Other option could be to keep seperate copies in all VMs and refresh it using a hhtp get call to all VMs whenever the data changes in the DB. Now the question is , is there a way to access in a shared manner between all the VMs ? Or am I mssing something very obvious here? or is it not doable ? Piyush R. ---
**Author:** ![piyush\_r](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/73ab20/32.png) [@piyush\_r](https://www.ruby-forum.com/u/piyush_r)\ **Post date:** [April 21, 2009, 2:12am UTC](https://www.ruby-forum.com/t/accessing-ruby-objects-across-vms/166008/2 "2009-04-21T02:12:56Z")
Thanks Joel. DRB seems a better option but I think Marshal load dump seems easier even though there is a performance degradation. Optimization is premature but I have to pull it off because there is limited hardware available to me for this project. Thanks Piyush ---
**Author:** ![piyush\_r](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/73ab20/32.png) [@piyush\_r](https://www.ruby-forum.com/u/piyush_r)\ **Post date:** [April 21, 2009, 2:00am UTC](https://www.ruby-forum.com/t/accessing-ruby-objects-across-vms/166008/3 "2009-04-21T02:00:03Z")
Piyush R. wrote: > 1. Storing in localmemcache > The problem with both of these options is that I need to store heavily > nested objects. If I do that in memcache I may have to do using something > like Marshal dump and load which is a little slow for my liking. > Other option could be to keep seperate copies in all VMs and refresh it > using a hhtp get call to all VMs whenever the data changes in the DB. > > Now the question is , is there a way to access in a shared manner between > all the VMs ? Or am I mssing something very obvious here? or is it not > doable ? AFAIK there’s no way for two VMs to share live, writable object storage. Looks like the choice is between deserializing on every read (opts 1 and 2) vs. deserializing on every write (your “other option”). So if reads outnumber writes, as they often do, the other option might be better. You could use drb (which does marshal over sockets) instead of http for this. Probably faster, and certainly easier to use. Use the drbunix:/path/to/socket protocol instead of tcp, and it will be even faster (maybe 50%, in my experience). YMMV, and standard cautions against premature optimization apply… ---
**Author:** ![piyush\_r](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/73ab20/32.png) [@piyush\_r](https://www.ruby-forum.com/u/piyush_r)\ **Post date:** [April 21, 2009, 2:55am UTC](https://www.ruby-forum.com/t/accessing-ruby-objects-across-vms/166008/4 "2009-04-21T02:55:37Z")
Piyush R. wrote: > Thanks Joel. > DRB seems a better option but I think Marshal load dump seems easier even > though there is a performance degradation. Marshal #load and #dump _is_ what drb is doing. ---
**Author:** ![piyush\_r](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/73ab20/32.png) [@piyush\_r](https://www.ruby-forum.com/u/piyush_r)\ **Post date:** [April 21, 2009, 9:29am UTC](https://www.ruby-forum.com/t/accessing-ruby-objects-across-vms/166008/5 "2009-04-21T09:29:09Z")
2009/4/21 Piyush R. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid): > DRB seems a better option but I think Marshal load dump seems easier even > though there is a performance degradation. I am not sure what you mean by this. As Joel pointed out, DRb does use Marshal. You just need to decide which objects are remotely accessible and which should be sent over the wire. If you have a heavy concurrent application with frequent updates you must watch out for all sorts of consistency issues. It may turn out that it is better to use the database for maintaining integrity and do a per process caching of relevant data from the DB. Kind regards robert