Comment 0 for bug 727615

While our current policy is not unreasonable, it makes doing something elementary -- eliminating strictly unsafe hash-table accesses from a codebase far harder than it should be.

I propose the following:

1. Hash-tables should be synchronized by default, so that portable library code has a prayer of doing the right thing. Code that cannot pay the overhead of synchronization can still request unsychronized tables explicitly.

2. Synchronized hash-tables need to be safe to modify while iteration is happening in another thread.

WITH-LOCKED-HASH-TABLE is still needed to make interning into a hash-table work right

  (with-locked-hash-table (table)
    (or (gethash key table)
        (setf (gethash key table) value)))

but that is a user code correctness issue, not a "will this break horribly" issues as the above points.