Protect access to the taskid to deal with different threads. (#207)
Protect access to the taskid to deal with different threads. (#207)

The requests can be made on one thread, but the expire on another thread.
tsan flagged this potential race, so add the needed guards so the access
is as safe as possible given the system api's required usage.
google/gtm-session-fetcher,thomasvl/gtm-session-fetcher,google/gtm-session-fetcher,google/gtm-session-fetcher,thomasvl/gtm-session-fetcher,thomasvl/gtm-session-fetcher