illumos gate

Bryan writes, on dtrace-discuss and developers@

A longstanding problem that we have had is that enablings on defunct
providers (e.g., USDT probes on dead processes) are not reaped: the
probes will exist as long as there exists an enabling for them. When
processes are turning over frequently (or when enablings are
long-running), this can clog up the probe space to the point that
DTrace probe creation will silently fail (an absolutely maddening
failure mode). This has been hit several times over the years (we
were nailed by it on our build machines at Fishworks) -- so when Theo
Schlossnagle mentioned to me that he was getting killed by this
problem in an environment with rapidly turning over Postgres
processes, I was embarrassed that I hadn't tackled it earlier. As it
turns out, it was a tad thorny for locking reasons

we should integrate this fix, now that Adam has reviewed.

Theo, at omniti, is especially interested in getting it in soon.