I would add another point to the reasoning: 5) Users can build application level rowlocks using HBase's CAS primitives, or ZooKeeper / Curator recipes (since ZooKeeper is always available in HBase environments), and these don't suffer the problems mentioned.
On Tue, Dec 11, 2012 at 2:37 PM, Andrew Purtell <[email protected]> wrote: > I agree with all points. +1 > > > On Tue, Dec 11, 2012 at 2:00 PM, Ted Yu <[email protected]> wrote: > >> Including user mailing list. >> >> On Tue, Dec 11, 2012 at 1:52 PM, Gregory Chanan <[email protected] >> >wrote: >> >> > Over in HBASE-7263 there has been some discussion about removing support >> > for explicit RowLocks in 0.96. This would involve the following: >> > - Remove lockRow/unlockRow functions in HTable and similar >> > - Remove constructors for Put/Delete/Increment/Get that take RowLocks >> > - functions in HRegion no longer take lockIds (checkAndPut, append, >> > increment, etc). This would affect coprocessors that call directly into >> > those functions. >> > >> > I have a patch in HBASE-7315 with the details. >> > >> > This would violate our usual rule of deprecating a feature one release >> > before removing. The reasoning is as follows: >> > 1) RowLocks are broken >> > They are only kept in the memory associated with the region, so on a >> > split, region move, RS crash, they just disappear >> > >> > 2) 0.96 is special >> > Now seems like a good time to clean things up since we've made some >> > incompatible changes already (e.g. protobufing) and we could have a >> cleaner >> > client implementation >> > >> > 3) RowLocks have been deprecated "in spirit" for awhile >> > Here's a post from 2009 cautioning against their use: >> > http://bb10.com/java-hadoop-hbase-user/2009-09/msg00239.html >> > and a more recent example: >> > http://permalink.gmane.org/gmane.comp.java.hadoop.hbase.user/23488 >> > >> > 4) RowLocks are hard to use effectively >> > Clients can deadlock or starve themselves, either by forgetting to >> release >> > the RowLocks or by starving other non-contending row operations by >> > occupying server handlers stuck waiting to acquire the locks. >> > >> > Thoughts? >> > >> > Greg >> > >> > > > > -- > Best regards, > > - Andy > > Problems worthy of attack prove their worth by hitting back. - Piet Hein > (via Tom White) > > -- Best regards, - Andy Problems worthy of attack prove their worth by hitting back. - Piet Hein (via Tom White)
