[jira] Commented: (DERBY-4519) Infinite loop in StreamFileContainer.writeColumn

["Knut Anders Hatlen (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DERBY-4519?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12802307#action_12802307 ] 

Knut Anders Hatlen commented on DERBY-4519:
-------------------------------------------

Another problem with this code is that it uses InputStream.available() to decide the size of the read buffer. If available() returns 0 (which it is allowed to) an empty read buffer is used, and this will also lead to an infinite loop, I think.

The patch looks like an improvement, though. Minor nit: Calling the read(byte[]) method that takes no offset/length arguments would be equivalent to read(bufData,0,bufferLen) and slightly simpler.

> Infinite loop in StreamFileContainer.writeColumn
> ------------------------------------------------
>
>                 Key: DERBY-4519
>                 URL: https://issues.apache.org/jira/browse/DERBY-4519
>             Project: Derby
>          Issue Type: Bug
>          Components: Store
>    Affects Versions: 10.0.2.1, 10.1.3.1, 10.2.2.0, 10.3.3.0, 10.4.2.0, 10.5.3.0, 10.6.0.0
>            Reporter: Kristian Waagan
>            Assignee: Kristian Waagan
>             Fix For: 10.6.0.0
>
>         Attachments: derby-4519-1a-argument_swap.diff
>
>
> The offset and length argument have been swapped in the calls to InputStream.read(byte,offset, length) and write(byte,offset, length). This code is inside a do-while (true) loop, and the only normal way out is when InputStream.read returns -1. This will never happen since the stream is asked to read zero bytes. Derby ends up eating up all available CPU, limited to a single core / CPU.
> The bug hasn't been observed because Derby is materializing all values when calling this code. Enabling streaming capabilities in the sorter revealed it.

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