New MongoDB alerts and advisories page
alerts.mongodb.org
New MongoDB alerts and advisories page
1–10 of 13 posts
Re: New MongoDB alerts and advisories page
#2Is this page new as of this past week [edit: its new as of today]? Either way, every large software project should always try to have some standard page for this sort of information, so kudos to them for now having one (and its a visible link on the homepage too).
Re: New MongoDB alerts and advisories page
#3Is this page new as of this past week [edit: its new as of today]? Either way, every large software project should always try to have some standard page for this sort of information, so kudos to them for now having one (and its a visible link on the homepage too).
it's new.
Re: New MongoDB alerts and advisories page
#4I read recently that mongo has a global lock on write. That was news to me, does anyone have more info?
Re: New MongoDB alerts and advisories page
#5I read recently that mongo has a global lock on write. That was news to me, does anyone have more info?
Currently, there is a global read/write lock. MongoDB does extensive yielding and tracking of on vs. off disk to mitigate the effects of this. In subsequent versions (2.2) , we'll be lowering the scope of this lock as well.
Re: New MongoDB alerts and advisories page
#6I read recently that mongo has a global lock on write. That was news to me, does anyone have more info?
Currently, there is a global read/write lock. MongoDB does extensive yielding and tracking of on vs. off disk to mitigate the effects of this. In subsequent versions (2.2) , we'll be lowering the scope of this lock as well.
So only one read at a time?
Re: New MongoDB alerts and advisories page
#7Earlier quoted context omitted.
Currently, there is a global read/write lock. MongoDB does extensive yielding and tracking of on vs. off disk to mitigate the effects of this. In subsequent versions (2.2) , we'll be lowering the scope of this lock as well.
So only one read at a time?
You can read concurrently, but the write lock will block read locks.
http://www.mongodb.org/display/DOCS/How+does+concurrency+wor...
Re: New MongoDB alerts and advisories page
#8Earlier quoted context omitted.
Currently, there is a global read/write lock. MongoDB does extensive yielding and tracking of on vs. off disk to mitigate the effects of this. In subsequent versions (2.2) , we'll be lowering the scope of this lock as well.
So only one read at a time?
No, a read write lock is a lock designed so that multiple readers can hold the lock, but only a single writer can hold the lock. That way readers know no write is taking place(as many reads as you like can take place), and writers know they have exclusive access.
Re: New MongoDB alerts and advisories page
#9Earlier quoted context omitted.
So only one read at a time?
You can read concurrently, but the write lock will block read locks. http://www.mongodb.org/display/DOCS/How+does+concurrency+wor...
If you have a lot of writes, this is a KILLER.
You need to be very careful here.
Note, even with Read-Slaves, you are STILL blocked, since each write replicates to each Read-Slave, and counts as a blocking-write on that slave while it replicates in.
We dramatically increased application performance when we refactored to remove a lot of little writes for things like caching, and moved them to memcache.
Re: New MongoDB alerts and advisories page
#10Earlier quoted context omitted.
So only one read at a time?
No, a read write lock is a lock designed so that multiple readers can hold the lock, but only a single writer can hold the lock. That way readers know no write is taking place(as many reads as you like can take place), and writers know they have exclusive access.
Yes, but keep in mind that while the write lock is in place, reads are blocked, not just writes.