[tbb-dev] Very very slow tor-browser-build build; catastrophic recursion in rbm?

Nicolas Vigier boklm at mars-attacks.org
Wed Feb 12 19:17:16 UTC 2020

On Tue, 11 Feb 2020, David Fifield wrote:

> To my untrained eye it looks like there is some kind of exponential
> recursion happening around the RBM::config_p function. See here, where
> in building one project the function was called 89 million times:
> https://people.torproject.org/~dcf/graphs/nytprof-rbm-20200212-94fce31e/#subs_table
> Clicking through to the per-line view, we see that 45 million of those
> calls were from RBM::get_target, and most of the rest were from
> RBM::config:
> https://people.torproject.org/~dcf/graphs/nytprof-rbm-20200212-94fce31e/root-tor-browser-build-rbm-lib-RBM-pm-8-line.html#89

After looking at this more closely, I am expecting RBM::config_p to be
called a lot of times (although maybe not 89 millions times), but I
would not expect that more than half of this would be from RBM::get_target.

So I opened an other ticket about that:

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