yapxue opened a new issue, #15782:
URL: https://github.com/apache/pulsar/issues/15782
**Describe the bug**
When a broker is shutdowm suddenly, for example it holds ledger L1 and LAC
is E0, has pending writes E1 and E2, WQ is B1, B2, B3. E1 has been written to
B1, E2 has been written to B3. Then before bookkeeper client opens a new ledger
and it is supposed to try to recover L1. There maybe some problem for current
recovery policy. Recovery has two principles.
principle 1: One positive bookie will be judged as recoverable.
principle 2: (WQ-AQ)+1 negative bookie will be judged as unrecoverable.
positive bookie mean it has the entry, negative bookie mean it will respond
NoSuchEntry when you query the entry.
For WQ=3 and only one bookie has the entry, it will be judged as recoverable
if its response arrives earlier than the other two. It will be judged as
unrecoverable and truncated if its response arrives later than the pther two.
For the same condition is has two behavior.
Here is an example. when a broker is shutdowm suddenly, it holds ledger L1
and LAC is E0, has pending writes E1 and E2, WQ is B1, B2, B3. E1 has been
written to B1, E2 has been written to B3. Then before bookkeeper client opens a
new ledger and it is supposed to try to recover L1. Then it may have the
following two cases.
case 1:
B1 B2.
B3 is recoverable?
t1. OK Waiting response.
Waiting response Yes
case 2:
B1 B2.
B3 is recoverable?
t1. NoSuchEntry Waiting response. Waiting
response Need more response
t2. NoSuchEntry.
Waiting response No.
case 1 and case 2 has different results. For case 1, client think the entry
is not written success but bookie has the entry, this can cause inconsitency of
clien and server.
**Expected behavior**
For the same condition, recovery should have the same results, not probably
can recover, probably cann't recover.
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