Re: Bug in 0.1.3 scanner?

Wed, 23 Jul 2008 15:51:32 -0700

I'd expect a little pause as client goes and sets up scanner on the next region but your log seems to be showing the client waiting so long that when it eventually gets through, server says I know nothing of the lease. What if you up the client lease timeout? I wonder if filters are tripping things up? Is it the first region transition or sometime after the first/second transition? Were 'other scanners on other tasks' that were frozen trying to get the same region? Do you know the problematic region? You need to pull on the reporter.progress in your map task if its completion takes longer than the TaskTracker lease interval. 
St.Ack


Daniel Leffel wrote:

Breakthrough in the mystery?

The key that it fails on just happens to be the last key in the region....

Is opening the scanner on the new region the problem?



On Tue, Jul 22, 2008 at 12:18 PM, Daniel Leffel <[EMAIL PROTECTED]>wrote:


OK. So, I didn't notice the IOE subclassing, so that explained the fact I
wasn't catching it.

However, somethign is still definitely going on. The scanner at some point
gets "stuck". See the next's being called:
2008-07-22 13:34:18,274 DEBUG
org.apache.hadoop.hbase.filter.WhileMatchRowFilter: FilterNotNull on
cols:{hierarcy:[EMAIL PROTECTED]  Result = false
2008-07-22 13:34:18,284 DEBUG
org.apache.hadoop.hbase.filter.WhileMatchRowFilter: this.filterAllRemaining
is now: false
2008-07-22 13:34:18,285 DEBUG
org.apache.hadoop.hbase.filter.WhileMatchRowFilter: FilterNotNull on
cols:{hierarcy:[EMAIL PROTECTED]  Result = false
2008-07-22 13:34:18,292 DEBUG org.apache.hadoop.hbase.filter.StopRowFilter:
Filter result for rowKey: 1121874.  Result: false
2008-07-22 13:34:18,292 DEBUG
org.apache.hadoop.hbase.filter.WhileMatchRowFilter: this.filterAllRemaining
is now: false
2008-07-22 13:34:18,292 DEBUG
org.apache.hadoop.hbase.filter.WhileMatchRowFilter: Filter on
rowKey:1121874.  Result = false
2008-07-22 13:34:18,292 DEBUG org.apache.hadoop.hbase.filter.StopRowFilter:
Filter result for rowKey: 1121874.  Result: false
2008-07-22 13:34:18,292 DEBUG
org.apache.hadoop.hbase.filter.WhileMatchRowFilter: this.filterAllRemaining
is now: false
2008-07-22 13:34:18,292 DEBUG
org.apache.hadoop.hbase.filter.WhileMatchRowFilter: Filter on
rowKey:1121874, colKey: hierarcy:immediate_parents, data: [EMAIL PROTECTED]
Result = false
2008-07-22 13:34:18,324 DEBUG org.apache.hadoop.hbase.filter.StopRowFilter:
Filter result for rowKey: 11218740.  Result: false
2008-07-22 13:34:18,324 DEBUG
org.apache.hadoop.hbase.filter.WhileMatchRowFilter: this.filterAllRemaining
is now: false
2008-07-22 13:34:18,325 DEBUG
org.apache.hadoop.hbase.filter.WhileMatchRowFilter: Filter on
rowKey:11218740.  Result = false
2008-07-22 13:34:18,325 DEBUG org.apache.hadoop.hbase.filter.StopRowFilter:
Filter result for rowKey: 11218740.  Result: false
2008-07-22 13:34:18,325 DEBUG
org.apache.hadoop.hbase.filter.WhileMatchRowFilter: this.filterAllRemaining
is now: false
2008-07-22 13:34:18,325 DEBUG
org.apache.hadoop.hbase.filter.WhileMatchRowFilter: Filter on
rowKey:11218740, colKey: hierarcy:immediate_parents, data: [EMAIL PROTECTED]
Result = false
2008-07-22 13:34:18,334 DEBUG
org.apache.hadoop.hbase.filter.WhileMatchRowFilter: this.filterAllRemaining
is now: false
2008-07-22 13:34:18,334 DEBUG
org.apache.hadoop.hbase.filter.WhileMatchRowFilter: FilterNotNull on
cols:{hierarcy:[EMAIL PROTECTED]  Result = false
2008-07-22 13:34:18,744 DEBUG
org.apache.hadoop.hbase.filter.WhileMatchRowFilter: Successfully read a
sub-filter of type: org.apache.hadoop.hbase.filter.StopRowFilter
2008-07-22 13:34:18,745 DEBUG
org.apache.hadoop.hbase.filter.WhileMatchRowFilter: Successfully read a
sub-filter of type: org.apache.hadoop.hbase.filter.StopRowFilter
2008-07-22 13:34:18,745 DEBUG
org.apache.hadoop.hbase.filter.WhileMatchRowFilter: Resetting.
2008-07-22 13:34:18,758 DEBUG org.apache.hadoop.hbase.filter.StopRowFilter:
Filter result for rowKey: 11391639.  Result: false
2008-07-22 13:34:18,758 DEBUG
org.apache.hadoop.hbase.filter.WhileMatchRowFilter: this.filterAllRemaining
is now: false
2008-07-22 13:34:18,758 DEBUG
org.apache.hadoop.hbase.filter.WhileMatchRowFilter: Filter on
rowKey:11391639.  Result = false
2008-07-22 13:34:18,759 DEBUG org.apache.hadoop.hbase.filter.StopRowFilter:
Filter result for rowKey: 11391639.  Result: false
2008-07-22 13:34:18,759 DEBUG
org.apache.hadoop.hbase.filter.WhileMatchRowFilter: this.filterAllRemaining
is now: false
2008-07-22 13:34:18,759 DEBUG
org.apache.hadoop.hbase.filter.WhileMatchRowFilter: Filter on
rowKey:11391639, colKey: hierarcy:immediate_parents, data: [EMAIL PROTECTED]
Result = false
2008-07-22 13:34:18,779 DEBUG org.apache.hadoop.hbase.filter.StopRowFilter:
Filter result for rowKey: 1139164.  Result: false
2008-07-22 13:34:18,779 DEBUG
org.apache.hadoop.hbase.filter.WhileMatchRowFilter: this.filterAllRemaining
is now: false
2008-07-22 13:34:18,779 DEBUG
org.apache.hadoop.hbase.filter.WhileMatchRowFilter: Filter on
rowKey:1139164.  Result = false
2008-07-22 13:34:18,779 DEBUG org.apache.hadoop.hbase.filter.StopRowFilter:
Filter result for rowKey: 1139164.  Result: false
2008-07-22 13:34:18,779 DEBUG
org.apache.hadoop.hbase.filter.WhileMatchRowFilter: this.filterAllRemaining
is now: false
2008-07-22 13:34:18,779 DEBUG
org.apache.hadoop.hbase.filter.WhileMatchRowFilter: Filter on
rowKey:1139164, colKey: hierarcy:immediate_parents, data: [EMAIL PROTECTED]
Result = false
2008-07-22 13:34:18,782 DEBUG
org.apache.hadoop.hbase.filter.WhileMatchRowFilter: this.filterAllRemaining
is now: false
2008-07-22 13:34:18,783 DEBUG
org.apache.hadoop.hbase.filter.WhileMatchRowFilter: FilterNotNull on
cols:{hierarcy:[EMAIL PROTECTED]  Result = false


Then at some point, next just hangs and the next entry in the log is
expiration:
2008-07-22 13:44:18,015 INFO org.apache.hadoop.hbase.Leases:
regionserver/0.0.0.0:60020.leaseChecker lease expired
-4780003109149242775/-4780003109149242775
2008-07-22 13:44:18,015 INFO org.apache.hadoop.hbase.HRegionServer: Scanner
-4780003109149242775 lease expired
2008-07-22 13:44:18,015 INFO org.apache.hadoop.hbase.Leases:
regionserver/0.0.0.0:60020.leaseChecker lease expired
-8543632393752004827/-8543632393752004827
2008-07-22 13:44:18,015 INFO org.apache.hadoop.hbase.HRegionServer: Scanner
-8543632393752004827 lease expired
2008-07-22 13:44:18,015 INFO org.apache.hadoop.hbase.Leases:
regionserver/0.0.0.0:60020.leaseChecker lease expired
-3834469434163616397/-3834469434163616397
2008-07-22 13:44:18,015 INFO org.apache.hadoop.hbase.HRegionServer: Scanner
-3834469434163616397 lease expired
2008-07-22 13:44:28,024 INFO org.apache.hadoop.hbase.Leases:
regionserver/0.0.0.0:60020.leaseChecker lease expired
-6363251876420626143/-6363251876420626143
2008-07-22 13:44:28,024 INFO org.apache.hadoop.hbase.HRegionServer: Scanner
-6363251876420626143 lease expired
2008-07-22 13:44:28,024 INFO org.apache.hadoop.hbase.Leases:
regionserver/0.0.0.0:60020.leaseChecker lease expired
-4332402553799574820/-4332402553799574820
2008-07-22 13:44:28,024 INFO org.apache.hadoop.hbase.HRegionServer: Scanner
-4332402553799574820 lease expired
2008-07-22 13:44:28,024 INFO org.apache.hadoop.hbase.Leases:
regionserver/0.0.0.0:60020.leaseChecker lease expired
7541512102009958038/7541512102009958038
2008-07-22 13:44:28,024 INFO org.apache.hadoop.hbase.HRegionServer: Scanner
7541512102009958038 lease expired
2008-07-22 13:44:28,025 INFO org.apache.hadoop.hbase.Leases:
regionserver/0.0.0.0:60020.leaseChecker lease expired
-6673102874800967750/-6673102874800967750
2008-07-22 13:44:28,025 INFO org.apache.hadoop.hbase.HRegionServer: Scanner
-6673102874800967750 lease expired
2008-07-22 13:44:28,025 INFO org.apache.hadoop.hbase.Leases:
regionserver/0.0.0.0:60020.leaseChecker lease expired
9143807894343107328/9143807894343107328
2008-07-22 13:44:28,025 INFO org.apache.hadoop.hbase.HRegionServer: Scanner
9143807894343107328 lease expired

Now interestingly, the map task doesn't know about the expired lease until
a number of minutes later when it finally tries to call next:
2008-07-22 14:54:29,062 INFO org.apache.hadoop.ipc.Server: IPC Server
handler 8 on 60020, call next(-4780003109149242775) from
10.252.242.159:60900: error:
org.apache.hadoop.hbase.UnknownScannerException: Name: -4780003109149242775
org.apache.hadoop.hbase.UnknownScannerException: Name: -4780003109149242775
        at
org.apache.hadoop.hbase.HRegionServer.next(HRegionServer.java:1506)
        at sun.reflect.GeneratedMethodAccessor3.invoke(Unknown Source)
        at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at
org.apache.hadoop.hbase.ipc.HbaseRPC$Server.call(HbaseRPC.java:413)
        at org.apache.hadoop.ipc.Server$Handler.run(Server.java:901)
2008-07-22 14:54:29,070 INFO org.apache.hadoop.ipc.Server: IPC Server
handler 3 on 60020, call close(-4780003109149242775) from
10.252.242.159:60900: error:
org.apache.hadoop.hbase.UnknownScannerException: -4780003109149242775
org.apache.hadoop.hbase.UnknownScannerException: -4780003109149242775
        at
org.apache.hadoop.hbase.HRegionServer.close(HRegionServer.java:1616)
        at sun.reflect.GeneratedMethodAccessor11.invoke(Unknown Source)
        at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at
org.apache.hadoop.hbase.ipc.HbaseRPC$Server.call(HbaseRPC.java:413)
        at org.apache.hadoop.ipc.Server$Handler.run(Server.java:901)


Even more interestingly is that the other scanners for the other tasks were
also "frozen" during the time and their leases expire too.

Inside the iteration, it's pretty simple stuff happening - string
manipulation mostly and a put into a bdb - takes <10ms.

The only other suspect piece of code is a reporter.progress() which I had
to put or else the task tracker thinks the task is dead. I've not had
trouble with reporter.progress() to date...

Any thoughts?


On Tue, Jul 22, 2008 at 11:22 AM, stack <[EMAIL PROTECTED]> wrote:


Hey D:

TableInputFormat#TableRecordReader#next looks like it lets out
IOExceptions.  UnknownScannerException subclasses IOE so I'd think it should
bubble up into your map task.

Paste in the exception you found in your logs.  That might help figure
whats going on.

St.Ack


Daniel Leffel wrote:


I've had a little bit of weird behavior.

I am opening a scanner in the configure method of a Map task to load a
simple little in-memory map (I'd love to this with in-memory column
stores,
but that's another story ;-).

Anyway, the scanner iterates over 4 million rows or so and I've verified
next is being called multiple times per second. However, at the same
record
every time (after around 6 minutes of iteration), the scanner throws an
UnknownScannerException in the log (I see it in the log), but rather than
throw the exception to the Map task, next just returns false and the loop
ends (making it exceptionally difficult to detect if the scanner finished
scanning or not). Increasing the regionserver timeout has most definitely
solved the issue, but shouldn't calling next reset the timeout anyway?

Such a frustrating problem!

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