Is elb a copy in each core? If not, GPU_indexbuf_set_tri_verts doesn't seem to be thread-safe.

In D11290#293245, @Germano Cavalcante (mano-wii) wrote:

Is elb a copy in each core? If not, GPU_indexbuf_set_tri_verts doesn't seem to be thread-safe.

elb is the full buffer. as long as elt_index or mlt_index don't overlap (and they don't) there is no issue about thread safety. As I see it threads store on other location in the elb. This is how the other threaded extractors work.

I mean. Within the function we have this that is not good concurrently:

if (builder->index_len < idx) {
    builder->index_len = idx;
}

Between checking if builder->index_len < idx and setting the value, builder->index_len can change in another thread.
We have "atomic" functions for this, but they generally penalize performance a lot.

In D11290#293256, @Germano Cavalcante (mano-wii) wrote:

I mean. Within the function we have this that is not good concurrently:

if (builder->index_len < idx) {
    builder->index_len = idx;
}

Between checking if builder->index_len < idx and setting the value, builder->index_len can change in another thread.
We have "atomic" functions for this, but they generally penalize performance a lot.

Ah yes. If that is the case we should store the max index locally and have an option to save it during finish.