A concurrency engine for the open web.
thread::main RUNNING
2048
0.3ms
LOCKED
99.97%
When a thread's local queue empties, it doesn't idle. It reaches into a neighbor's queue and steals work -- a controlled act of piracy that keeps every core saturated. The engine treats idle cycles as a moral failure. No thread rests while work exists anywhere in the system.
Long-running tasks are sliced at microsecond boundaries. The scheduler doesn't ask permission; it takes control. Each yield point is a negotiation between throughput and fairness -- the engine favors neither, balancing both through adaptive time-slicing that learns from workload patterns.
When a low-priority thread holds a lock that a high-priority thread needs, the engine temporarily promotes the blocker. Priority inheritance isn't a workaround -- it's a principle. The system refuses to let scheduling decisions create deadlocks through neglect.
Threads develop relationships with CPU cores. Once a thread runs on a core, the scheduler remembers. Cache lines warm, branch predictors train, and the thread's next scheduling decision favors the same core. Affinity is memory. Memory is speed.
A mutex is a bottleneck disguised as a safety mechanism. Every lock acquisition is a bet that the critical section will be short. The engine monitors contention ratios in real-time, splitting hot mutexes into sharded locks when contention exceeds thresholds that would make lesser systems choke.
Compare-and-swap loops replace mutex acquisitions. The queue doesn't lock; it retries. Each failed CAS is information -- a signal that contention exists, that the topology should adapt. Lock-free doesn't mean conflict-free. It means conflicts are resolved through persistence, not exclusion.
Threads arrive at a barrier and wait. Not because they're slow, but because synchronization demands patience. The barrier is a meeting point -- all threads must be present before any can proceed. It's the engine's way of saying: no one moves until everyone is ready.
At the lowest level, the engine speaks in atomics. Loads and stores that complete in a single bus cycle, invisible to the rest of the system. Memory ordering constraints -- acquire, release, sequentially consistent -- form a grammar of guarantees that prevent the chaos of concurrent mutation.
Every core maintains its own view of memory. When one core writes, the others must learn. The MESI protocol -- Modified, Exclusive, Shared, Invalid -- orchestrates a constant conversation between caches. The engine doesn't fight this conversation; it shapes it, aligning data structures along cache line boundaries to minimize cross-core chatter.
Two variables on the same cache line, written by different cores. Each write invalidates the other's cache, creating a ping-pong of coherence messages that destroys performance. The engine pads structures to cache line boundaries -- 64 bytes of intentional waste that prevents accidental coupling between independent threads.
The CPU reorders instructions for speed. The programmer assumes sequential execution. Memory fences bridge this gap -- compiler and hardware barriers that say: everything before this point is visible before anything after. Fences are expensive. The engine uses them surgically, only where correctness demands order.
All threads converge. The engine rests.