[gpfsug-discuss] DMAPI multi-thread safe

[Wayne Sawdon]

> From: "Tomasz.Wolski at ts.fujitsu.com" <Tomasz.Wolski at ts.fujitsu.com>
>
> Could you please tell me if the DMAPI implementation for GPFS is
> multi-thread safe? Are there any limitation towards using multiple
> threads within a single DM application process?
> For example: DM events are processed by multiple threads, which call
> dm* functions for manipulating file attributes – will there be any
> problem when two threads try to access the same file at the same time?
>
> Is the libdmapi thread safe?
>

With the possible exception of dm_init_service it should be thread safe.
Dmapi does offer access rights to allow or prevent concurrent access to a
file.
If you are not using the access rights, internally Spectrum Scale will
serialize
the dmapi calls like it would serialize for posix -- some calls will
proceed in
parallel (e.g. reads, non-overlapping writes) and some will be serialized
(e.g. EA updates).

-Wayne
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