Re: [Jdbm-general] JDBM questions

[Alex B. <boi...@in...>]

Rickard =D6berg wrote:
>=20
> Would it be possible to add a method to explicitly flush the tx log?=20
> That way I could lock the whole thing, flush the tx log, and then do=20
> backup of a single file. That'd be awesome!

Yes, I will look into that.

> I have a couple of generic performance improvements I=20
> did for Jisp which might work well here as well, such as an=20
> unsynchronized block-oriented ByteArrayOutputStream. Comes in handy=20
> especially with large output streams.

Cool.  Assuming we can license the code with the JDBM license -- you=20
would still retain copyright -- then I would gladly integrate it.

> The problem with regard to fragmentation that we have seen with Jisp ar=
e:
> *) Since it wasn't paged we got loads of small holes which were never=20
> reused (i.e. small object created, then removed, then hole is never=20
> reused again). Compaction every month or so typically did give us about=
=20
> 20-30% extra storage. If I remember correctly JDBM uses paging (i.e.=20
> fix-sized blocks instead of size equal to output size), so this should=20
> be a non-issue here.

Yes, that's correct.  Physical allocation is page-based.

> But, the first three priorities for us are:
> 1) Stability
> 2) Stability
> 3) Stability
>=20
> We are using this in a CMS which is being beat on quite heavily (our=20
> webhotel has 15 customers whose websites are in one database). We've ha=
d=20
> some (nightmare) crashes with Jisp, and if JDBM can prove to be more=20
> stable we would be truly happy :-)
>=20

I will let you be the judge of that.

alex