[jira] [Commented] (HDFS-1445) Batch the calls in DataStorage to FileUtil.createHardLink(), so we call it once per directory instead of once per file
[ https://issues.apache.org/jira/browse/HDFS-1445?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13022497#comment-13022497 ] Hudson commented on HDFS-1445: -- Integrated in Hadoop-Hdfs-trunk #643 (See [https://builds.apache.org/hudson/job/Hadoop-Hdfs-trunk/643/]) Batch the calls in DataStorage to FileUtil.createHardLink(), so we call it once per directory instead of once per file -- Key: HDFS-1445 URL: https://issues.apache.org/jira/browse/HDFS-1445 Project: Hadoop HDFS Issue Type: Sub-task Components: data-node Affects Versions: 0.20.2 Reporter: Matt Foley Assignee: Matt Foley Fix For: 0.23.0 Attachments: HDFS-1445-trunk.v22_hdfs_2-of-2.patch It was a bit of a puzzle why we can do a full scan of a disk in about 30 seconds during FSDir() or getVolumeMap(), but the same disk took 11 minutes to do Upgrade replication via hardlinks. It turns out that the org.apache.hadoop.fs.FileUtil.createHardLink() method does an outcall to Runtime.getRuntime().exec(), to utilize native filesystem hardlink capability. So it is forking a full-weight external process, and we call it on each individual file to be replicated. As a simple check on the possible cost of this approach, I built a Perl test script (under Linux on a production-class datanode). Perl also uses a compiled and optimized p-code engine, and it has both native support for hardlinks and the ability to do exec. - A simple script to create 256,000 files in a directory tree organized like the Datanode, took 10 seconds to run. - Replicating that directory tree using hardlinks, the same way as the Datanode, took 12 seconds using native hardlink support. - The same replication using outcalls to exec, one per file, took 256 seconds! - Batching the calls, and doing 'exec' once per directory instead of once per file, took 16 seconds. Obviously, your mileage will vary based on the number of blocks per volume. A volume with less than about 4000 blocks will have only 65 directories. A volume with more than 4K and less than about 250K blocks will have 4200 directories (more or less). And there are two files per block (the data file and the .meta file). So the average number of files per directory may vary from 2:1 to 500:1. A node with 50K blocks and four volumes will have 25K files per volume, or an average of about 6:1. So this change may be expected to take it down from, say, 12 minutes per volume to 2. -- This message is automatically generated by JIRA. For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] Commented: (HDFS-1445) Batch the calls in DataStorage to FileUtil.createHardLink(), so we call it once per directory instead of once per file
[ https://issues.apache.org/jira/browse/HDFS-1445?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13008593#comment-13008593 ] Hudson commented on HDFS-1445: -- Integrated in Hadoop-Hdfs-trunk-Commit #563 (See [https://hudson.apache.org/hudson/job/Hadoop-Hdfs-trunk-Commit/563/]) HDFS-1445. Batch the calls in DataStorage to FileUtil.createHardLink(). Contributed by Matt Foley. Batch the calls in DataStorage to FileUtil.createHardLink(), so we call it once per directory instead of once per file -- Key: HDFS-1445 URL: https://issues.apache.org/jira/browse/HDFS-1445 Project: Hadoop HDFS Issue Type: Sub-task Components: data-node Affects Versions: 0.20.2 Reporter: Matt Foley Assignee: Matt Foley Fix For: 0.23.0 Attachments: HDFS-1445-trunk.v22_hdfs_2-of-2.patch It was a bit of a puzzle why we can do a full scan of a disk in about 30 seconds during FSDir() or getVolumeMap(), but the same disk took 11 minutes to do Upgrade replication via hardlinks. It turns out that the org.apache.hadoop.fs.FileUtil.createHardLink() method does an outcall to Runtime.getRuntime().exec(), to utilize native filesystem hardlink capability. So it is forking a full-weight external process, and we call it on each individual file to be replicated. As a simple check on the possible cost of this approach, I built a Perl test script (under Linux on a production-class datanode). Perl also uses a compiled and optimized p-code engine, and it has both native support for hardlinks and the ability to do exec. - A simple script to create 256,000 files in a directory tree organized like the Datanode, took 10 seconds to run. - Replicating that directory tree using hardlinks, the same way as the Datanode, took 12 seconds using native hardlink support. - The same replication using outcalls to exec, one per file, took 256 seconds! - Batching the calls, and doing 'exec' once per directory instead of once per file, took 16 seconds. Obviously, your mileage will vary based on the number of blocks per volume. A volume with less than about 4000 blocks will have only 65 directories. A volume with more than 4K and less than about 250K blocks will have 4200 directories (more or less). And there are two files per block (the data file and the .meta file). So the average number of files per directory may vary from 2:1 to 500:1. A node with 50K blocks and four volumes will have 25K files per volume, or an average of about 6:1. So this change may be expected to take it down from, say, 12 minutes per volume to 2. -- This message is automatically generated by JIRA. For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] Commented: (HDFS-1445) Batch the calls in DataStorage to FileUtil.createHardLink(), so we call it once per directory instead of once per file
[ https://issues.apache.org/jira/browse/HDFS-1445?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13005792#comment-13005792 ] Hadoop QA commented on HDFS-1445: - -1 overall. Here are the results of testing the latest attachment http://issues.apache.org/jira/secure/attachment/12470696/HDFS-1445-trunk.v22_hdfs_2-of-2.patch against trunk revision 1080380. +1 @author. The patch does not contain any @author tags. +1 tests included. The patch appears to include 3 new or modified tests. +1 javadoc. The javadoc tool did not generate any warning messages. +1 javac. The applied patch does not increase the total number of javac compiler warnings. +1 findbugs. The patch does not introduce any new Findbugs (version 1.3.9) warnings. +1 release audit. The applied patch does not increase the total number of release audit warnings. -1 core tests. The patch failed these core unit tests: org.apache.hadoop.hdfs.TestFileConcurrentReader -1 contrib tests. The patch failed contrib unit tests. +1 system test framework. The patch passed system test framework compile. Test results: https://hudson.apache.org/hudson/job/PreCommit-HDFS-Build/250//testReport/ Findbugs warnings: https://hudson.apache.org/hudson/job/PreCommit-HDFS-Build/250//artifact/trunk/build/test/findbugs/newPatchFindbugsWarnings.html Console output: https://hudson.apache.org/hudson/job/PreCommit-HDFS-Build/250//console This message is automatically generated. Batch the calls in DataStorage to FileUtil.createHardLink(), so we call it once per directory instead of once per file -- Key: HDFS-1445 URL: https://issues.apache.org/jira/browse/HDFS-1445 Project: Hadoop HDFS Issue Type: Sub-task Components: data-node Affects Versions: 0.20.2 Reporter: Matt Foley Assignee: Matt Foley Fix For: 0.23.0 Attachments: HDFS-1445-trunk.v22_hdfs_2-of-2.patch It was a bit of a puzzle why we can do a full scan of a disk in about 30 seconds during FSDir() or getVolumeMap(), but the same disk took 11 minutes to do Upgrade replication via hardlinks. It turns out that the org.apache.hadoop.fs.FileUtil.createHardLink() method does an outcall to Runtime.getRuntime().exec(), to utilize native filesystem hardlink capability. So it is forking a full-weight external process, and we call it on each individual file to be replicated. As a simple check on the possible cost of this approach, I built a Perl test script (under Linux on a production-class datanode). Perl also uses a compiled and optimized p-code engine, and it has both native support for hardlinks and the ability to do exec. - A simple script to create 256,000 files in a directory tree organized like the Datanode, took 10 seconds to run. - Replicating that directory tree using hardlinks, the same way as the Datanode, took 12 seconds using native hardlink support. - The same replication using outcalls to exec, one per file, took 256 seconds! - Batching the calls, and doing 'exec' once per directory instead of once per file, took 16 seconds. Obviously, your mileage will vary based on the number of blocks per volume. A volume with less than about 4000 blocks will have only 65 directories. A volume with more than 4K and less than about 250K blocks will have 4200 directories (more or less). And there are two files per block (the data file and the .meta file). So the average number of files per directory may vary from 2:1 to 500:1. A node with 50K blocks and four volumes will have 25K files per volume, or an average of about 6:1. So this change may be expected to take it down from, say, 12 minutes per volume to 2. -- This message is automatically generated by JIRA. For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] Commented: (HDFS-1445) Batch the calls in DataStorage to FileUtil.createHardLink(), so we call it once per directory instead of once per file
[ https://issues.apache.org/jira/browse/HDFS-1445?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13005938#comment-13005938 ] Matt Foley commented on HDFS-1445: -- I examined the three failures noted: org.apache.hadoop.hdfs.TestFileConcurrentReader.testUnfinishedBlockCRCErrorNormalTransfer org.apache.hadoop.hdfsproxy.TestAuthorizationFilter.testPathPermit org.apache.hadoop.hdfsproxy.TestAuthorizationFilter.testPathPermitQualified The two hdfsproxy issues don't seem to have anything to do with this patch nor the associated patch for HADOOP-7133. The TestFileConcurrentReader issue also doesn't, and the noted failure, Too many open files, does not occur when I run it locally even on a very small box. Request approval of this patch despite these unit test failures, since they appear unrelated. Batch the calls in DataStorage to FileUtil.createHardLink(), so we call it once per directory instead of once per file -- Key: HDFS-1445 URL: https://issues.apache.org/jira/browse/HDFS-1445 Project: Hadoop HDFS Issue Type: Sub-task Components: data-node Affects Versions: 0.20.2 Reporter: Matt Foley Assignee: Matt Foley Fix For: 0.23.0 Attachments: HDFS-1445-trunk.v22_hdfs_2-of-2.patch It was a bit of a puzzle why we can do a full scan of a disk in about 30 seconds during FSDir() or getVolumeMap(), but the same disk took 11 minutes to do Upgrade replication via hardlinks. It turns out that the org.apache.hadoop.fs.FileUtil.createHardLink() method does an outcall to Runtime.getRuntime().exec(), to utilize native filesystem hardlink capability. So it is forking a full-weight external process, and we call it on each individual file to be replicated. As a simple check on the possible cost of this approach, I built a Perl test script (under Linux on a production-class datanode). Perl also uses a compiled and optimized p-code engine, and it has both native support for hardlinks and the ability to do exec. - A simple script to create 256,000 files in a directory tree organized like the Datanode, took 10 seconds to run. - Replicating that directory tree using hardlinks, the same way as the Datanode, took 12 seconds using native hardlink support. - The same replication using outcalls to exec, one per file, took 256 seconds! - Batching the calls, and doing 'exec' once per directory instead of once per file, took 16 seconds. Obviously, your mileage will vary based on the number of blocks per volume. A volume with less than about 4000 blocks will have only 65 directories. A volume with more than 4K and less than about 250K blocks will have 4200 directories (more or less). And there are two files per block (the data file and the .meta file). So the average number of files per directory may vary from 2:1 to 500:1. A node with 50K blocks and four volumes will have 25K files per volume, or an average of about 6:1. So this change may be expected to take it down from, say, 12 minutes per volume to 2. -- This message is automatically generated by JIRA. For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] Commented: (HDFS-1445) Batch the calls in DataStorage to FileUtil.createHardLink(), so we call it once per directory instead of once per file
[ https://issues.apache.org/jira/browse/HDFS-1445?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=12992642#comment-12992642 ] Hadoop QA commented on HDFS-1445: - -1 overall. Here are the results of testing the latest attachment http://issues.apache.org/jira/secure/attachment/12470696/HDFS-1445-trunk.v22_hdfs_2-of-2.patch against trunk revision 1068968. +1 @author. The patch does not contain any @author tags. +1 tests included. The patch appears to include 3 new or modified tests. +1 javadoc. The javadoc tool did not generate any warning messages. -1 javac. The patch appears to cause tar ant target to fail. -1 findbugs. The patch appears to cause Findbugs (version 1.3.9) to fail. +1 release audit. The applied patch does not increase the total number of release audit warnings. -1 core tests. The patch failed these core unit tests: -1 contrib tests. The patch failed contrib unit tests. -1 system test framework. The patch failed system test framework compile. Test results: https://hudson.apache.org/hudson/job/PreCommit-HDFS-Build/157//testReport/ Console output: https://hudson.apache.org/hudson/job/PreCommit-HDFS-Build/157//console This message is automatically generated. Batch the calls in DataStorage to FileUtil.createHardLink(), so we call it once per directory instead of once per file -- Key: HDFS-1445 URL: https://issues.apache.org/jira/browse/HDFS-1445 Project: Hadoop HDFS Issue Type: Sub-task Components: data-node Affects Versions: 0.20.2 Reporter: Matt Foley Assignee: Matt Foley Fix For: 0.22.0 Attachments: HDFS-1445-trunk.v22_common_1-of-2.patch, HDFS-1445-trunk.v22_hdfs_2-of-2.patch It was a bit of a puzzle why we can do a full scan of a disk in about 30 seconds during FSDir() or getVolumeMap(), but the same disk took 11 minutes to do Upgrade replication via hardlinks. It turns out that the org.apache.hadoop.fs.FileUtil.createHardLink() method does an outcall to Runtime.getRuntime().exec(), to utilize native filesystem hardlink capability. So it is forking a full-weight external process, and we call it on each individual file to be replicated. As a simple check on the possible cost of this approach, I built a Perl test script (under Linux on a production-class datanode). Perl also uses a compiled and optimized p-code engine, and it has both native support for hardlinks and the ability to do exec. - A simple script to create 256,000 files in a directory tree organized like the Datanode, took 10 seconds to run. - Replicating that directory tree using hardlinks, the same way as the Datanode, took 12 seconds using native hardlink support. - The same replication using outcalls to exec, one per file, took 256 seconds! - Batching the calls, and doing 'exec' once per directory instead of once per file, took 16 seconds. Obviously, your mileage will vary based on the number of blocks per volume. A volume with less than about 4000 blocks will have only 65 directories. A volume with more than 4K and less than about 250K blocks will have 4200 directories (more or less). And there are two files per block (the data file and the .meta file). So the average number of files per directory may vary from 2:1 to 500:1. A node with 50K blocks and four volumes will have 25K files per volume, or an average of about 6:1. So this change may be expected to take it down from, say, 12 minutes per volume to 2. -- This message is automatically generated by JIRA. - For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] Commented: (HDFS-1445) Batch the calls in DataStorage to FileUtil.createHardLink(), so we call it once per directory instead of once per file
[ https://issues.apache.org/jira/browse/HDFS-1445?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=12972970#action_12972970 ] M. C. Srivas commented on HDFS-1445: If no one really uses hardlinks, why don't you get rid of this altogether? Batch the calls in DataStorage to FileUtil.createHardLink(), so we call it once per directory instead of once per file -- Key: HDFS-1445 URL: https://issues.apache.org/jira/browse/HDFS-1445 Project: Hadoop HDFS Issue Type: Sub-task Components: data-node Affects Versions: 0.20.2 Reporter: Matt Foley Assignee: Matt Foley Fix For: 0.22.0 It was a bit of a puzzle why we can do a full scan of a disk in about 30 seconds during FSDir() or getVolumeMap(), but the same disk took 11 minutes to do Upgrade replication via hardlinks. It turns out that the org.apache.hadoop.fs.FileUtil.createHardLink() method does an outcall to Runtime.getRuntime().exec(), to utilize native filesystem hardlink capability. So it is forking a full-weight external process, and we call it on each individual file to be replicated. As a simple check on the possible cost of this approach, I built a Perl test script (under Linux on a production-class datanode). Perl also uses a compiled and optimized p-code engine, and it has both native support for hardlinks and the ability to do exec. - A simple script to create 256,000 files in a directory tree organized like the Datanode, took 10 seconds to run. - Replicating that directory tree using hardlinks, the same way as the Datanode, took 12 seconds using native hardlink support. - The same replication using outcalls to exec, one per file, took 256 seconds! - Batching the calls, and doing 'exec' once per directory instead of once per file, took 16 seconds. Obviously, your mileage will vary based on the number of blocks per volume. A volume with less than about 4000 blocks will have only 65 directories. A volume with more than 4K and less than about 250K blocks will have 4200 directories (more or less). And there are two files per block (the data file and the .meta file). So the average number of files per directory may vary from 2:1 to 500:1. A node with 50K blocks and four volumes will have 25K files per volume, or an average of about 6:1. So this change may be expected to take it down from, say, 12 minutes per volume to 2. -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.
[jira] Commented: (HDFS-1445) Batch the calls in DataStorage to FileUtil.createHardLink(), so we call it once per directory instead of once per file
[ https://issues.apache.org/jira/browse/HDFS-1445?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=12972925#action_12972925 ] Todd Lipcon commented on HDFS-1445: --- We could alternatively just add some calls to the new NativeIO library from HADOOP-6978 to call link(2) via JNI. Then we avoid the fork entirely. Batch the calls in DataStorage to FileUtil.createHardLink(), so we call it once per directory instead of once per file -- Key: HDFS-1445 URL: https://issues.apache.org/jira/browse/HDFS-1445 Project: Hadoop HDFS Issue Type: Sub-task Components: data-node Affects Versions: 0.20.2 Reporter: Matt Foley Assignee: Matt Foley Fix For: 0.22.0 It was a bit of a puzzle why we can do a full scan of a disk in about 30 seconds during FSDir() or getVolumeMap(), but the same disk took 11 minutes to do Upgrade replication via hardlinks. It turns out that the org.apache.hadoop.fs.FileUtil.createHardLink() method does an outcall to Runtime.getRuntime().exec(), to utilize native filesystem hardlink capability. So it is forking a full-weight external process, and we call it on each individual file to be replicated. As a simple check on the possible cost of this approach, I built a Perl test script (under Linux on a production-class datanode). Perl also uses a compiled and optimized p-code engine, and it has both native support for hardlinks and the ability to do exec. - A simple script to create 256,000 files in a directory tree organized like the Datanode, took 10 seconds to run. - Replicating that directory tree using hardlinks, the same way as the Datanode, took 12 seconds using native hardlink support. - The same replication using outcalls to exec, one per file, took 256 seconds! - Batching the calls, and doing 'exec' once per directory instead of once per file, took 16 seconds. Obviously, your mileage will vary based on the number of blocks per volume. A volume with less than about 4000 blocks will have only 65 directories. A volume with more than 4K and less than about 250K blocks will have 4200 directories (more or less). And there are two files per block (the data file and the .meta file). So the average number of files per directory may vary from 2:1 to 500:1. A node with 50K blocks and four volumes will have 25K files per volume, or an average of about 6:1. So this change may be expected to take it down from, say, 12 minutes per volume to 2. -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.
