On 2010-11-11 13:26, Regis wrote:
On 2010-11-11 13:13, Charles Lee wrote:
The cache is good for the performance. But when the cache meet link,
there
will be some difficult situation. The patch has attached is a
workaround for
the specified test case. The good choose for the timeout should bed
discussed.
On Thu, Nov 11, 2010 at 7:30 AM, Guillermo Cabrera (JIRA)
<j...@apache.org>wrote:
Reducing timeout value in CanonicalPatchCache to fix a file not found
error
in Hadoop common
--------------------------------------------------------------------------------------------
Key: HARMONY-6675
URL: https://issues.apache.org/jira/browse/HARMONY-6675
Project: Harmony
Issue Type: New Feature
Environment: SLE v. 11, Apache Harmony 6
Reporter: Guillermo Cabrera
Priority: Minor
Testing Harmony Select (r1022137) with Hadoop common, we ran across the
following error:
java.lang.RuntimeException: Error while running command to get file
permissions : org.apache.hadoop.util.Shell$ExitCodeException: /bin/ls:
/tmp/test1/file: No such file or directory
Charles Lee (Apache Harmony developer) provided us with the following
answer:
"For all the test case failures in
org.apache.hadoop.fs.TestLocalFSFileContextSymlink, the root cause is we
have a CanonicalPathCache under the File, so the file canonical path
will be
wrong if the test case highly stressed, (I remember the cache time is
set to
10 minute)."
His patch to fix this issue has been attached.
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I think we should provide a way to configure this cache: enable/disable
it and timeout, something like
-Dorg.apache.harmony.canonpath.cache.timeout=60, this property could be
overwritten at run time.
Also the default value of timeout, 10 minutes seems too long, maybe
reduce to one minute or half minute is reasonable for the most of
applications?
I propose following patch, which configure canonical path cache via system
property 'org.apache.harmony.file.canonical.path.cache.timeout', set it to zero
could disable the cache completely. And I also reduce default timeout from 10
minutes to 30 seconds. If no one object, I'll commit this path soon.
Index:
modules/luni/src/main/java/org/apache/harmony/luni/internal/io/FileCanonPathCache.java
=====================================================================
---
modules/luni/src/main/java/org/apache/harmony/luni/internal/io/FileCanonPathCache.java
+++
modules/luni/src/main/java/org/apache/harmony/luni/internal/io/FileCanonPathCache.java
@@ -55,9 +55,29 @@ public class FileCanonPathCache {
private static Object lock = new Object();
/**
- * Expired time.
+ * Expired time, 0 disable this cache.
*/
- private static long timeout = 600000;
+ private static long timeout = 30000;
+
+ /**
+ * Whether to enable this cache.
+ */
+ private static boolean isEnable = true;
+
+ public static final String FILE_CANONICAL_PATH_CACHE_TIMEOUT =
"org.apache.harmony.file.canonical.path.cache.timeout";
+
+ static {
+ String value = System.getProperty(FILE_CANONICAL_PATH_CACHE_TIMEOUT);
+ try {
+ timeout = Long.parseLong(value);
+ } catch (NumberFormatException e) {
+ // use default timeout value
+ }
+
+ if (timeout <= 0) {
+ isEnable = false;
+ }
+ }
/**
* Retrieve element from cache.
@@ -68,6 +88,10 @@ public class FileCanonPathCache {
*
*/
public static String get(String path) {
+ if (!isEnable) {
+ return null;
+ }
+
CacheElement element = null;
synchronized (lock) {
element = cache.get(path);
@@ -104,6 +128,10 @@ public class FileCanonPathCache {
* the canonical path of <code>path</code>.
*/
public static void put(String path, String canonicalPath) {
+ if (!isEnable) {
+ return;
+ }
+
CacheElement element = new CacheElement(canonicalPath);
synchronized (lock) {
if (cache.size() >= CACHE_SIZE) {
@@ -120,6 +148,10 @@ public class FileCanonPathCache {
* Remove all elements from cache.
*/
public static void clear() {
+ if (!isEnable) {
+ return;
+ }
+
synchronized (lock) {
cache.clear();
list.clear();
@@ -132,5 +164,8 @@ public class FileCanonPathCache {
public static void setTimeout(long timeout) {
FileCanonPathCache.timeout = timeout;
+ if (timeout <= 0) {
+ isEnable = false;
+ }
}
}
--
Best Regards,
Regis.
