[ https://issues.apache.org/jira/browse/IO-279?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16076219#comment-16076219 ]
ASF GitHub Bot commented on IO-279: ----------------------------------- GitHub user myyron opened a pull request: https://github.com/apache/commons-io/pull/40 IO-279: Added ignoreNew parameter on instantiating Tailer. Encountered this bug today when we try to tail a file that is being modified even though there is no new content being added. You can merge this pull request into a Git repository by running: $ git pull https://github.com/myyron/commons-io IO_279 Alternatively you can review and apply these changes as the patch at: https://github.com/apache/commons-io/pull/40.patch To close this pull request, make a commit to your master/trunk branch with (at least) the following in the commit message: This closes #40 ---- commit 79dd3567811f0f155c43cb88f331489b85e6189c Author: mlatorilla <mlatori...@sunpowercorp.com> Date: 2017-07-06T08:44:57Z IO-279: Added ignoreNew parameter on instantiating Tailer. ---- > Tailer erroneously considers file as new > ---------------------------------------- > > Key: IO-279 > URL: https://issues.apache.org/jira/browse/IO-279 > Project: Commons IO > Issue Type: Bug > Affects Versions: 2.0.1, 2.4 > Reporter: Sergio Bossa > Attachments: disable_resetting.patch, fix-tailer.patch, IO-279.patch, > modify-test-fixed.patch, modify-test.patch > > > Tailer sometimes erroneously considers the tailed file as new, forcing a > repositioning at the start of the file: I'm still unable to reproduce this in > a test case, because it only happens to me with huge log files during Apache > Tomcat startup. > This is the piece of code causing the problem: > {code} > // See if the file needs to be read again > if (length > position) { > // The file has more content than it did last time > last = System.currentTimeMillis(); > position = readLines(reader); > } else if (FileUtils.isFileNewer(file, last)) { > /* This can happen if the file is truncated or overwritten > * with the exact same length of information. In cases like > * this, the file position needs to be reset > */ > position = 0; > reader.seek(position); // cannot be null here > // Now we can read new lines > last = System.currentTimeMillis(); > position = readLines(reader); > } > {code} > What probably happens is that the new file content is about to be written on > disk, the date is already updated but content is still not flushed, so actual > length is untouched and there you go. > In other words, I think there should be some better method to verify the > condition above, rather than relying only on dates: keeping and comparing the > hash code of the latest line may be a solution, but may hurt performances ... > other ideas? -- This message was sent by Atlassian JIRA (v6.4.14#64029)