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From "Randall Theobald (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (IO-530) Tailer pegs CPU if file disappears and doesn't come back
Date Tue, 21 Mar 2017 19:56:41 GMT

     [ https://issues.apache.org/jira/browse/IO-530?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Randall Theobald updated IO-530:
--------------------------------
    Attachment: io-530.patch

Simple patch to add delay to the tight loop.

> Tailer pegs CPU if file disappears and doesn't come back
> --------------------------------------------------------
>
>                 Key: IO-530
>                 URL: https://issues.apache.org/jira/browse/IO-530
>             Project: Commons IO
>          Issue Type: Bug
>    Affects Versions: 2.5
>            Reporter: Randall Theobald
>            Priority: Critical
>         Attachments: io-530.patch
>
>
> I ran into a situation where a bug in my log rotation leads to the tailed file being
renamed, but the original file name does not re-appear (new log entries still go to the renamed
log file). This uncovered a bug in the Tailer class. In this case, tailer enters a tight loop
trying to re-open the file:
> {code}
> while (getRun()) {
>                 final boolean newer = FileUtils.isFileNewer(file, last); // IO-279, must
be done first
>                 // Check the file length to see if it was rotated
>                 final long length = file.length();
>                 if (length < position) {
>                     // File was rotated
>                     listener.fileRotated();
>                     // Reopen the reader after rotation ensuring that the old file is
closed iff we re-open it
>                     // successfully
>                     try (RandomAccessFile save = reader) {
>                         reader = new RandomAccessFile(file, RAF_MODE);
>                         // At this point, we're sure that the old file is rotated
>                         // Finish scanning the old file and then we'll start with the
new one
>                         try {
>                             readLines(save);
>                         }  catch (IOException ioe) {
>                             listener.handle(ioe);
>                         }
>                         position = 0;
>                     } catch (final FileNotFoundException e) {
>                         // in this case we continue to use the previous reader and position
values
>                         listener.fileNotFound();
>                     }
>                     continue;
> {code}
> Since a non-existent file returns a length of zero, we keep entering this top loop, trying
to open the missing file, getting a FileNotFoundException and starting over.
> There should be some delay here.



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