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https://issues.apache.org/jira/browse/BOOKKEEPER-101?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13146460#comment-13146460
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[email protected] commented on BOOKKEEPER-101:
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bq. On 2011-11-08 18:22:42, Dhruba Borthakur wrote:
bq. >
bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/Bookie.java, line
561
bq. > <https://reviews.apache.org/r/2594/diff/2/?file=56350#file56350line561>
bq. >
bq. > Can we pl get some javadoc here that specifies the precise semantics
of the two new flags. Looking at the code actually makes me understand the
semantics, but it will be better if we can create a javadoc here, especially
since this is a public api, isn't it?
bq. >
The client api is in org.apache.bookkeeper.client. This is serverside, so not
really public. Some javadoc here would be useful for developers though.
bq. On 2011-11-08 18:22:42, Dhruba Borthakur wrote:
bq. >
bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/Bookie.java, line
570
bq. > <https://reviews.apache.org/r/2594/diff/2/?file=56350#file56350line570>
bq. >
bq. > I have a major question here: suppose client A is executing a
Bookie.addEntry(), it first checked that handle is not fencedout and is about
to go ahead to write the entry into the log. It is about to execute
handle.addEntry().
bq. >
bq. > Now another client B issued a Bookie.addEntry(enableFencing=true).
This client sets the fecing flag in the handle and then finishes doing the
handle.addEntry() for its own entry. It now returns to the client and client B
thinks that it has successfully fenced out other clients.
bq. >
bq. > Now the first thread that was processing the request for client A
wakes up and finishes the handle.addEntry() call. Can this happen? If so, then
we have a problem.
bq. >
bq. >
Ah, thanks for reminding me of this. It isn't a problem now, as this part of
the bookie is single threaded, but its best to address this now, than having to
scrabble to fix it if/when we move to multithreaded bookies.
bq. On 2011-11-08 18:22:42, Dhruba Borthakur wrote:
bq. >
bookkeeper-server/src/main/java/org/apache/bookkeeper/client/BookKeeper.java,
line 268
bq. > <https://reviews.apache.org/r/2594/diff/2/?file=56354#file56354line268>
bq. >
bq. > Some java doc here would be really realyl helpful
I'll add.
bq. On 2011-11-08 18:22:42, Dhruba Borthakur wrote:
bq. >
bookkeeper-server/src/main/java/org/apache/bookkeeper/proto/BookieClient.java,
line 74
bq. > <https://reviews.apache.org/r/2594/diff/2/?file=56364#file56364line74>
bq. >
bq. > some javadocs on the meaning of "options" would be nice.
I'll add.
bq. On 2011-11-08 18:22:42, Dhruba Borthakur wrote:
bq. >
bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/LedgerDescriptor.java,
line 46
bq. > <https://reviews.apache.org/r/2594/diff/2/?file=56352#file56352line46>
bq. >
bq. > maybe we should use the volatile keyword here?
I'll add. As I said above, this part is single threaded, so it shouldn't make a
difference, but no harm in future proofing.
bq. On 2011-11-08 18:22:42, Dhruba Borthakur wrote:
bq. >
bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/BookieException.java,
line 69
bq. > <https://reviews.apache.org/r/2594/diff/2/?file=56351#file56351line69>
bq. >
bq. > Is it easy to print which client (client identifier, ip address,
etc) has fenced off? This helps debugging.
The client identifier of who fenced it? It would require modifications to the
LedgerDescriptor. Perhaps we could log a message when the ledger itself gets
fenced, and the person debugging could match it up.
bq. On 2011-11-08 18:22:42, Dhruba Borthakur wrote:
bq. >
bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/Bookie.java, line
590
bq. > <https://reviews.apache.org/r/2594/diff/2/?file=56350#file56350line590>
bq. >
bq. > is there a use-case why we need the enableFencing call for both
addEntry() and readEntry()? Isn't it enough to have this flag only for
readEntry() call?
There shouldn't be. I think I added it to addEntry because I was thinking I
could get away with just one flag for fencing and recovery add, which I
couldn't. I don't think there's any case were addEntry could actually fence,
because by the time we get to it, readEntry() should have have hit the bookie.
I need to think about this a little more.
- Ivan
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-----------------------------------------------------------
On 2011-11-04 17:40:53, Ivan Kelly wrote:
bq.
bq. -----------------------------------------------------------
bq. This is an automatically generated e-mail. To reply, visit:
bq. https://reviews.apache.org/r/2594/
bq. -----------------------------------------------------------
bq.
bq. (Updated 2011-11-04 17:40:53)
bq.
bq.
bq. Review request for bookkeeper.
bq.
bq.
bq. Summary
bq. -------
bq.
bq. BookKeeper is designed for use as a Write ahead log. In systems with a
primary/backup architecture, the primary will write state updates to the WAL.
If the primary dies the backup comes online, reads the WAL to get the latest
state and starts serving requests. However, if the primary was only partitioned
from the network, or stuck in a long GC, a split brain occurs. Both primary and
backup can service client requests.
bq.
bq. Fencing(http://en.wikipedia.org/wiki/Fencing_%28computing%29) ensures that
this cannot happen. With fencing, the backup can close the WAL of the primary,
and cause any subsequent attempt by the primary to write to the WAL to give an
error.
bq.
bq.
bq. This addresses bug BOOKKEEPER-101.
bq. https://issues.apache.org/jira/browse/BOOKKEEPER-101
bq.
bq.
bq. Diffs
bq. -----
bq.
bq. bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/Bookie.java
d651894
bq.
bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/BookieException.java
292617e
bq.
bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/LedgerDescriptor.java
024cac3
bq.
bookkeeper-server/src/main/java/org/apache/bookkeeper/client/BKException.java
d7c8f67
bq.
bookkeeper-server/src/main/java/org/apache/bookkeeper/client/BookKeeper.java
a1fbab7
bq.
bookkeeper-server/src/main/java/org/apache/bookkeeper/client/BookKeeperAdmin.java
b3eb5b9
bq.
bookkeeper-server/src/main/java/org/apache/bookkeeper/client/LedgerCreateOp.java
6f72e47
bq.
bookkeeper-server/src/main/java/org/apache/bookkeeper/client/LedgerHandle.java
8c2a54f
bq.
bookkeeper-server/src/main/java/org/apache/bookkeeper/client/LedgerMetadata.java
328c7ca
bq.
bookkeeper-server/src/main/java/org/apache/bookkeeper/client/LedgerOpenOp.java
a68856c
bq.
bookkeeper-server/src/main/java/org/apache/bookkeeper/client/LedgerRecoveryOp.java
7465c52
bq.
bookkeeper-server/src/main/java/org/apache/bookkeeper/client/PendingAddOp.java
eddd760
bq.
bookkeeper-server/src/main/java/org/apache/bookkeeper/client/PendingReadOp.java
385b16c
bq.
bookkeeper-server/src/main/java/org/apache/bookkeeper/client/ReadLastConfirmedOp.java
c2d4cee
bq.
bookkeeper-server/src/main/java/org/apache/bookkeeper/proto/BookieClient.java
d70ae27
bq.
bookkeeper-server/src/main/java/org/apache/bookkeeper/proto/BookieProtocol.java
873dafe
bq.
bookkeeper-server/src/main/java/org/apache/bookkeeper/proto/BookieServer.java
f1b3ad9
bq.
bookkeeper-server/src/main/java/org/apache/bookkeeper/proto/PerChannelBookieClient.java
2cd4de8
bq.
bookkeeper-server/src/test/java/org/apache/bookkeeper/client/LedgerCacheTest.java
07639aa
bq.
bookkeeper-server/src/test/java/org/apache/bookkeeper/client/TestFencing.java
PRE-CREATION
bq.
bookkeeper-server/src/test/java/org/apache/bookkeeper/proto/TestProtoVersions.java
f6cd8c9
bq.
bookkeeper-server/src/test/java/org/apache/bookkeeper/test/BaseTestCase.java
6bac569
bq.
bookkeeper-server/src/test/java/org/apache/bookkeeper/test/BookieClientTest.java
97dc2ab
bq.
bookkeeper-server/src/test/java/org/apache/bookkeeper/test/BookieRecoveryTest.java
ac54d9a
bq.
bookkeeper-server/src/test/java/org/apache/bookkeeper/test/ConcurrentLedgerTest.java
ebb17d2
bq.
bookkeeper-server/src/test/java/org/apache/bookkeeper/test/LoopbackClient.java
85822bf
bq.
hedwig-server/src/main/java/org/apache/hedwig/server/benchmark/BookieBenchmark.java
18319d7
bq.
bq. Diff: https://reviews.apache.org/r/2594/diff
bq.
bq.
bq. Testing
bq. -------
bq.
bq.
bq. Thanks,
bq.
bq. Ivan
bq.
bq.
> Add Fencing to Bookkeeper
> -------------------------
>
> Key: BOOKKEEPER-101
> URL: https://issues.apache.org/jira/browse/BOOKKEEPER-101
> Project: Bookkeeper
> Issue Type: New Feature
> Reporter: Ivan Kelly
> Assignee: Ivan Kelly
> Fix For: 4.0.0
>
> Attachments: BOOKKEEPER-101.diff, BOOKKEEPER-101.diff
>
>
> BookKeeper is designed for use as a Write ahead log. In systems with a
> primary/backup architecture, the primary will write state updates to the WAL.
> If the primary dies the backup comes online, reads the WAL to get the latest
> state and starts serving requests. However, if the primary was only
> partitioned from the network, or stuck in a long GC, a split brain occurs.
> Both primary and backup can service client requests.
> Fencing(http://en.wikipedia.org/wiki/Fencing_%28computing%29) ensures that
> this cannot happen. With fencing, the backup can close the WAL of the
> primary, and cause any subsequent attempt by the primary to write to the WAL
> to give an error.
> We fence a ledger whenever it is opened by another client using
> BookKeeper#openLedger. BookKeeper#openLedgerNoRecovery will not fence.
> The opening client marks the ledger as fenced in zookeeper, and then sends a
> readEntry message to a all of bookies with the DO_FENCING flag set. Once at
> least 1 bookie in each possible quorum of bookies have responded, we can
> proceed with opening the ledger. Any subsequent attempt to write to the
> ledger will fail as it will not be able to write to a quorum without one of
> the bookie in the quorum responding with a ledger fenced error. The client
> will also be unable to change the quorum without seeing that the ledger has
> been marked as fenced in zookeeper.
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