stop using mmap for zip I/O

[Seán Coffey]

On 27/02/15 12:23, christos at zoulas.com wrote:
> On Feb 27,  9:51am, sean.coffey at oracle.com (=?windows-1252?Q?Se=E1n_Coffey?=) wrote:
> -- Subject: Re: stop using mmap for zip I/O
>
> | The sun.zip.disableMemoryMapping=true property helps with ZipFile class
> | only. There are other related issues in the ZipInput/Output streams.
> | Some code areas don't have synchronization and there are opportunities
> | for the underlying native zip resources to be freed which Java code then
> | tries to reference causing various SEGV. I've one or two areas of code
> | identified for tightening up and hope to get to it in coming weeks.
> | (long standing action item)
>
> Absolutely, there are unchecked lengths that are used to copy buffers...
Are those issues documented in a bug report somewhere ? Please share if not.

>
> | > So we catch the signal, right?  Maybe there's something I'm missing...
> | We don't catch/detect such SEGV's. Would it make sense, is it possible ?
>
> It is SIGBUS...
The issues I've been looking at are SEGV issues concerning multiple threads
operating on the same zip structure. (one freeing, while another is 
attempting access)

Variants of that issue exist also. E.g. :
https://bugs.openjdk.java.net/browse/JDK-8031691
https://bugs.openjdk.java.net/browse/JDK-8028216
https://bugs.openjdk.java.net/browse/JDK-7092196

regards,
Sean.

>
> christos