Lock unpickling of source ranges
Summary:
The source is shared across all threads running the torchscript
interpreter, so if several threads encounter errors at once, they will all race
to unpickle the source, leading to memory corruption.
Test Plan:
Model 217993215_0 is the problematic model; I wasn't able to repro
the crash with requests stored in Hive, but I could easily by adding my
devserver (SMC tier predictor.bertrand) as a shadow tier to the model's tier
(inference_platform.predictor_model.prod.bi.217993215_latest). (i.e., set
shadow_tier property to predictor.bertrand=1 to proxy 1% of traffic).
With this diff, the ASAN/TSAN errors go away.
Reviewed By: suo
Differential Revision: D31044009
fbshipit-source-id: 56f9ef3880e7cf09f334db71b4256e362b4de965
