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https://issues.apache.org/jira/browse/HDFS-12862?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17081647#comment-17081647
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Xiaoqiao He commented on HDFS-12862:
------------------------------------
Thanks [~brahmareddy] and [~weichiu] for reminder. Files another JIRA
HDFS-15272 to track backport and resolve this one to decouple branch-3.3
release progress.
> CacheDirective becomes invalid when NN restart or failover
> ----------------------------------------------------------
>
> Key: HDFS-12862
> URL: https://issues.apache.org/jira/browse/HDFS-12862
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: caching, hdfs
> Affects Versions: 2.7.1
> Environment:
> Reporter: Wang XL
> Assignee: Wang XL
> Priority: Major
> Labels: patch
> Fix For: 3.3.0
>
> Attachments: HDFS-12862-branch-2.7.1.001.patch,
> HDFS-12862-trunk.002.patch, HDFS-12862-trunk.003.patch,
> HDFS-12862-trunk.004.patch, HDFS-12862.005.patch, HDFS-12862.006.patch,
> HDFS-12862.007.patch, HDFS-12862.branch-3.1.patch
>
>
> The logic in FSNDNCacheOp#modifyCacheDirective is not correct. when modify
> cacheDirective,the expiration in directive may be a relative expiryTime, and
> EditLog will serial a relative expiry time.
> {code:java}
> // Some comments here
> static void modifyCacheDirective(
> FSNamesystem fsn, CacheManager cacheManager, CacheDirectiveInfo
> directive,
> EnumSet<CacheFlag> flags, boolean logRetryCache) throws IOException {
> final FSPermissionChecker pc = getFsPermissionChecker(fsn);
> cacheManager.modifyDirective(directive, pc, flags);
> fsn.getEditLog().logModifyCacheDirectiveInfo(directive, logRetryCache);
> }
> {code}
> But when SBN replay the log ,it will invoke
> FSImageSerialization#readCacheDirectiveInfo as a absolute expiryTime.It will
> result in the inconsistency .
> {code:java}
> public static CacheDirectiveInfo readCacheDirectiveInfo(DataInput in)
> throws IOException {
> CacheDirectiveInfo.Builder builder =
> new CacheDirectiveInfo.Builder();
> builder.setId(readLong(in));
> int flags = in.readInt();
> if ((flags & 0x1) != 0) {
> builder.setPath(new Path(readString(in)));
> }
> if ((flags & 0x2) != 0) {
> builder.setReplication(readShort(in));
> }
> if ((flags & 0x4) != 0) {
> builder.setPool(readString(in));
> }
> if ((flags & 0x8) != 0) {
> builder.setExpiration(
> CacheDirectiveInfo.Expiration.newAbsolute(readLong(in)));
> }
> if ((flags & ~0xF) != 0) {
> throw new IOException("unknown flags set in " +
> "ModifyCacheDirectiveInfoOp: " + flags);
> }
> return builder.build();
> }
> {code}
> In other words， fsn.getEditLog().logModifyCacheDirectiveInfo(directive,
> logRetryCache) may serial a relative expiry time,But
> builder.setExpiration(CacheDirectiveInfo.Expiration.newAbsolute(readLong(in)))
> read it as a absolute expiryTime.
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