Re: [libvirt] [PATCH v2] lib: Add note that bulk stats API queries may overrun RPC buffers

On Tue, May 23, 2017 at 05:07:40PM +0200, Michal Privoznik wrote: I don't think this is a reason at all. Libguestfs uses an RPC system which was modelled on the libvirt one, and has exactly the same problem with message size limits, except smaller -- 4MB and we've never had to increase it. We get around this by batching operations over messages as necessary (eg [1]). This adds a little complexity in the implementation of the API, but the point is that the complexity is entirely hidden to users of the APIs. Rich. [1] https://github.com/libguestfs/libguestfs/blob/master/lib/file.c#L375-L415 In this code, ‘guestfs_impl_lstatnslist’ is the publicly visible API (it's the implementation of the public API guestfs_lstatnslist). ‘guestfs_internal_lstatnslist’ is the message which travels over the RPC. The batching of 1000 requests per message was chosen based on pathname limits on Linux so that each request will always fit into a single message. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com libguestfs lets you edit virtual machines. Supports shell scripting, bindings from many languages. http://libguestfs.org