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https://issues.apache.org/jira/browse/HDFS-14567?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16904902#comment-16904902
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Wei-Chiu Chuang commented on HDFS-14567:
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{quote}
I feel here, before getting the configuration we are modifying last reload
time , so if there is any exception occurs while getting conf , modifying last
reload time before getting conf may give chance for error
so for a successful get of conf , we will modify last reload time . I feel this
will provide us the solution
"create a temporary acl file, once it closes, move it to kms-acls.xml" is not
required
{quote}
What I suggested will make sure it always reads a complete kms-acls.xml file.
That is, use the local file system semantics to ensure it is written
atomically, so you shouldn't see an exception loading the ACLs.
> If kms-acls is failed to load, and it will never be reload
> -----------------------------------------------------------
>
> Key: HDFS-14567
> URL: https://issues.apache.org/jira/browse/HDFS-14567
> Project: Hadoop HDFS
> Issue Type: Bug
> Reporter: hemanthboyina
> Assignee: hemanthboyina
> Priority: Major
> Attachments: HDFS-14567.patch
>
>
> Scenario : through one automation tool , we are generating kms-acls , though
> the generation of kms-acls is not completed , the system will detect a
> modification of kms-alcs and it will try to load
> Before getting the configuration we are modifiying last reload time , code
> shown below
> {code:java}
> private Configuration loadACLsFromFile() {
> LOG.debug("Loading ACLs file");
> lastReload = System.currentTimeMillis();
> Configuration conf = KMSConfiguration.getACLsConf();
> // triggering the resource loading.
> conf.get(Type.CREATE.getAclConfigKey());
> return conf;
> }{code}
> if the kms-acls file written within next 100ms , the changes will not be
> loaded as this condition "newer = f.lastModified() - time > 100" never meets
> because we have modified last reload time before getting the configuration
> {code:java}
> public static boolean isACLsFileNewer(long time) {
> boolean newer = false;
> String confDir = System.getProperty(KMS_CONFIG_DIR);
> if (confDir != null) {
> Path confPath = new Path(confDir);
> if (!confPath.isUriPathAbsolute()) {
> throw new RuntimeException("System property '" + KMS_CONFIG_DIR +
> "' must be an absolute path: " + confDir);
> }
> File f = new File(confDir, KMS_ACLS_XML);
> LOG.trace("Checking file {}, modification time is {}, last reload time is"
> + " {}", f.getPath(), f.lastModified(), time);
> // at least 100ms newer than time, we do this to ensure the file
> // has been properly closed/flushed
> newer = f.lastModified() - time > 100;
> }
> return newer;
> } {code}
>
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