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CPU Mining

mujina-miner can hash using your CPU instead of ASIC hardware. This is far too slow for real mining---a few MH/s versus TH/s for ASICs---but it lets you work with the full mining stack when you don't have hardware connected.

Use cases:

  • Development: Test code changes without physical boards
  • Pool testing: Verify connectivity and share submission
  • Scale testing: Spin up many instances to stress-test infrastructure
  • Learning: Understand mining workflows before investing in hardware

Enabling CPU Mining

Set MUJINA_CPUMINER_THREADS to enable CPU mining. The value specifies how many parallel hashing threads to run:

MUJINA_CPUMINER_THREADS=2 cargo run

Without this variable, the miner only looks for USB-connected ASIC hardware.

When running CPU-only, also set MUJINA_USB_DISABLE=1 to skip USB device discovery. This ignores any real mining boards you might have connected---they run at vastly different hashrates and would complicate testing. It also avoids USB-related noise on cloud systems:

MUJINA_CPUMINER_THREADS=2 \
MUJINA_USB_DISABLE=1 \
cargo run

Controlling CPU Usage

By default, each mining thread hashes for 50ms then sleeps for 50ms---a 50% duty cycle. This prevents CPU mining from starving other processes and avoids tripping CPU usage limits on cloud instances.

Adjust with MUJINA_CPUMINER_DUTY:

  • 100 --- Full speed, no throttling
  • 50 --- Hash half the time, sleep half (default)
  • 10 --- Light load, mostly idle

For testing, lower duty cycles work fine since you're not trying to maximize hashrate.

Testing Share Submission

Pools set share difficulty for ASIC-speed miners. A CPU running at MH/s instead of TH/s would wait days or weeks to find a share at typical pool difficulty. To test the share submission flow, use MUJINA_POOL_FORCED_RATE to artificially lower the target:

MUJINA_CPUMINER_THREADS=2 \
MUJINA_USB_DISABLE=1 \
MUJINA_POOL_FORCED_RATE=6 \
MUJINA_POOL_URL="stratum+tcp://pool.example.com:3333" \
MUJINA_POOL_USER="your-address.worker" \
cargo run

The value is target shares per minute. With MUJINA_POOL_FORCED_RATE=6, the miner targets one share every 10 seconds.

The forced rate wrapper intercepts jobs from the pool and replaces the share target with one computed to achieve your target rate at current hashrate. The pool still sets real difficulty for submitted shares; this just controls how often your miner finds candidates to submit.

Shares found this way will likely be rejected by the pool as below-difficulty. That's fine---you're testing connectivity and submission flow, not earning rewards.

Unreasonably fast rates (around 600 shares/min per thread or more) may not be achieved because the scheduler's internal share filter caps the per-thread rate to prevent flooding.

Running Without a Pool

Without MUJINA_POOL_URL, the miner uses a dummy job source that generates synthetic work:

MUJINA_CPUMINER_THREADS=2 \
MUJINA_USB_DISABLE=1 \
RUST_LOG=mujina_miner=debug \
cargo run

This exercises the full mining pipeline---job distribution, hashing, share detection---without any external dependencies.

Running in a Container

For deploying to cloud infrastructure or container orchestration platforms, see Container Image.

Environment Reference

Variable Description
MUJINA_CPUMINER_THREADS Number of mining threads; presence enables CPU mining
MUJINA_CPUMINER_DUTY Duty cycle percentage, 1-100 (default: 50)
MUJINA_USB_DISABLE Set to 1 to skip USB device discovery
MUJINA_POOL_FORCED_RATE Target share rate in shares/min