Maxwell-Guo commented on code in PR #4178:
URL: https://github.com/apache/cassandra/pull/4178#discussion_r2757878463
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src/java/org/apache/cassandra/config/DatabaseDescriptor.java:
##########
@@ -1763,7 +1780,7 @@ private static Pair<DiskAccessMode, Boolean>
resolveCommitLogWriteDiskAccessMode
File commitLogLocationDir = new File(commitLogLocation);
PathUtils.createDirectoriesIfNotExists(commitLogLocationDir.toPath());
- directIOSupported =
FileUtils.getBlockSize(commitLogLocationDir) > 0;
+ directIOSupported =
FileUtils.isDirectIOSupported(commitLogLocationDir);
Review Comment:
why you change the code here ?
##########
src/java/org/apache/cassandra/config/DatabaseDescriptor.java:
##########
@@ -1763,7 +1780,7 @@ private static Pair<DiskAccessMode, Boolean>
resolveCommitLogWriteDiskAccessMode
File commitLogLocationDir = new File(commitLogLocation);
PathUtils.createDirectoriesIfNotExists(commitLogLocationDir.toPath());
- directIOSupported =
FileUtils.getBlockSize(commitLogLocationDir) > 0;
+ directIOSupported =
FileUtils.isDirectIOSupported(commitLogLocationDir);
Review Comment:
I remembered that FileUtils#getBlockSize create a tmp file under commitlog
dir(also delete) to see if commitlog dir support direct io
Is there some possibility that data file and commitlog file are of different
filesystem ?
if FileUtils.isDirectIOSupported(commitLogLocationDir) return true can only
gurantee commitlog disk support direct io.
We used to make commitlog disk and data dir under different disk. cc
@aweisberg
##########
src/java/org/apache/cassandra/io/util/FileUtils.java:
##########
@@ -740,14 +741,54 @@ public static void deleteDirectoryIfEmpty(Path path)
throws IOException
}
}
+ public static boolean isDirectIOSupported(File file)
+ {
+ File testFile = null;
+ try
+ {
+ File dir = file.isDirectory() ? file : file.parent();
+ testFile = createTempFile("direct-io-test", ".tmp", dir);
+
+ // Direct IO requires knowing the block size for buffer alignment
+ if (blockSize(testFile) <= 0)
+ return false;
+
+ try (FileChannel channel = FileChannel.open(testFile.toPath(),
Review Comment:
1、so you open the channel ? just to see if we can use direct io ? and but if
the channel is successfully opend, when should we close it ?
2、 why the original method "blockSize(file) > 0" can not meet your need ?
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