cxzl25 opened a new pull request, #8416:
URL: https://github.com/apache/hadoop/pull/8416
### Description of PR
## Description
HDFS-16942 introduced `InvalidBlockReportLeaseException`, which the NameNode
now throws back to the DataNode via RPC when a block report is rejected due to
an invalid lease. On a DataNode that also includes HDFS-16942, the exception is
caught and `fullBlockReportLeaseId` is reset to 0, allowing the DN to request a
new lease on the next heartbeat and retry.
However, during a rolling upgrade where the NameNode has been upgraded (with
HDFS-16942) but DataNodes are still running an older version (without
HDFS-16942), the old DataNode code does not have the
`InvalidBlockReportLeaseException` handling branch in
`BPServiceActor.offerService()`. This causes the DN to enter an infinite
failure loop where it can never successfully send a full block report.
## Root Cause
In `BPServiceActor.offerService()`, the logic works as follows:
1. The DN requests a block report lease during heartbeat only when
`fullBlockReportLeaseId == 0`:
```java
boolean requestBlockReportLease = (fullBlockReportLeaseId == 0) &&
scheduler.isBlockReportDue(startTime);
```
2. After sending the block report, `fullBlockReportLeaseId` is reset to 0:
```java
if ((fullBlockReportLeaseId != 0) || forceFullBr) {
cmds = blockReport(fullBlockReportLeaseId);
fullBlockReportLeaseId = 0; // not reached if blockReport() throws
}
```
3. When the upgraded NN throws `InvalidBlockReportLeaseException`,
`blockReport()` propagates the exception. The `fullBlockReportLeaseId = 0` line
after the call is never executed.
4. The exception is caught by the generic `RemoteException` catch block. The
old DN code does not recognize `InvalidBlockReportLeaseException`, so
`fullBlockReportLeaseId` remains set to the stale invalid value.
5. On the next heartbeat iteration, because `fullBlockReportLeaseId != 0`,
`requestBlockReportLease` is `false` — the DN does not request a new lease. It
then attempts `blockReport()` again with the same stale lease, which the NN
rejects again. This repeats indefinitely.
### How was this patch tested?
Add test
### For code changes:
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