Bal Devnet Ab Test

BAL A/B Testing Wrapper

Compare erigon's parallel-execution throughput with vs without BAL (Block Access List) scheduling on a bal-devnet-N network. The flow is:

• Instance A (BAL) — default behaviour. Uses BAL hints from blocks to pre-populate version maps and schedule transactions optimistically.
• Instance B (No-BAL) — same code, but with IGNORE_BAL=true set in the environment, forcing the dependency-tracking scheduling path.

Both instances sync the same chain so gas/s, repeat%, abort, and invalid counters can be compared directly at chain tip.

Prerequisite: bring up Instance A

Use the launch-devnet skill with the BAL devnet URL the user provides (e.g. https://bal-devnet-3.ethpandaops.io). That skill discovers chain id, forks, bootnodes, and CL image from the network's config service, generates start/stop/clean scripts, and monitors progress. Do not duplicate that logic here.

When launch-devnet finishes, you'll have:

• $WORKDIR/ — Instance A working directory (default: ~/<devnet-name>/)
• $WORKDIR/devnet-info.txt — chain id, fork schedule, port offset chosen for Instance A
• $WORKDIR/inventory.json — bootnodes & peer endpoints (reused by Instance B)
• $WORKDIR/genesis.json, $WORKDIR/testnet-config/ — config artefacts (reused by Instance B)
• A running erigon (BAL) + CL pair

Confirm Instance A is past genesis and importing payloads before starting Instance B.

Set up Instance B (No-BAL)

launch-devnet writes Instance A's chosen offset to $WORKDIR/devnet-info.txt as port_offset: <N> (key/value format). Read it instead of guessing, then derive Instance B's offset by adding +300 (leaves room for +200/+300 ephemeral nodes the user might also be running). Verify the candidate ports with lsof (cross-platform — ss is Linux-only) before committing to the offset.

NOBAL_DIR="${WORKDIR}-nobal"

OFFSET_A=$(awk -F': *' '$1=="port_offset"{print $2}' "$WORKDIR/devnet-info.txt")
OFFSET_B=$(( OFFSET_A + 300 ))

# Re-check the +OFFSET_B family (TCP + UDP). Bump by +100 and retry on conflict.
for p in <each B port at +OFFSET_B>; do
  lsof -nP -iTCP:$p -sTCP:LISTEN >/dev/null 2>&1 && echo "TCP $p in use"
done
for p in <each B UDP port at +OFFSET_B>; do
  lsof -nP -iUDP:$p >/dev/null 2>&1 && echo "UDP $p in use"
done

mkdir -p "$NOBAL_DIR/erigon-data" "$NOBAL_DIR/cl-data"
cp    "$WORKDIR/genesis.json"     "$NOBAL_DIR/"
cp -r "$WORKDIR/testnet-config"   "$NOBAL_DIR/"
cp    "$WORKDIR/inventory.json"   "$NOBAL_DIR/"
cp    "$WORKDIR/devnet-info.txt"  "$NOBAL_DIR/devnet-info.txt"
# Update Instance B's metadata to record the new offset and IGNORE_BAL flag
sed -i.bak "s/^port_offset:.*/port_offset: $OFFSET_B/" "$NOBAL_DIR/devnet-info.txt" && rm "$NOBAL_DIR/devnet-info.txt.bak"
echo "ignore_bal: true" >> "$NOBAL_DIR/devnet-info.txt"

./build/bin/erigon init --datadir "$NOBAL_DIR/erigon-data" "$NOBAL_DIR/genesis.json"

Generate Instance B's start scripts the same way launch-devnet does, with these changes:

1. start-erigon.sh — add export IGNORE_BAL=true at the top of the script, before the erigon invocation. All other env vars stay the same as Instance A. Keep the exec ./build/bin/erigon … ending so the captured PID is the erigon PID (used by Cleanup).
2. All ports — use the +OFFSET_B family computed above (or whichever offset survived port-conflict checks). Update both the erigon flags and the CL flags.
3. CL container name — use ${DEVNET}-nobal-cl to avoid colliding with Instance A's container.
4. CL --execution-endpoint — point at Instance B's authrpc port, not A's.
5. CL --disable-enr-auto-update — required when running two CLs on the same host.

Start in the same order: erigon first, save its PID, poll for jwt.hex and authrpc bind (same loop as launch-devnet Step 8 — do not sleep), then CL.

cd "$NOBAL_DIR" && nohup bash start-erigon.sh > erigon-console.log 2>&1 &
echo $! > "$NOBAL_DIR/erigon.pid"

AUTHRPC_B=<authrpc port at +OFFSET_B>
for i in $(seq 1 60); do
  if [ -f "$NOBAL_DIR/erigon-data/jwt.hex" ] \
      && lsof -nP -iTCP:"$AUTHRPC_B" -sTCP:LISTEN >/dev/null 2>&1; then
    break
  fi
  sleep 1
done
[ -f "$NOBAL_DIR/erigon-data/jwt.hex" ] || { echo "Instance B jwt.hex not produced after 60s"; exit 1; }

cd "$NOBAL_DIR" && nohup bash start-cl.sh > cl-console.log 2>&1 &

Compare at chain tip

Wait until both instances are caught up (compare eth_blockNumber against the public RPC). Once both are at-head, the steady-state metrics in the execution log lines are what matter:

Expected: BAL instance should have lower repeat% and abort because BAL pre-populates the version map, reducing false conflicts. The gas/s delta is the net throughput impact.

Side-by-side log snapshot:

echo "=== BAL (A) ===" && \
  grep -E "parallel (executed|done)" "$WORKDIR/erigon-data/logs/erigon.log" | tail -3
echo
echo "=== No-BAL (B) ===" && \
  grep -E "parallel (executed|done)" "${WORKDIR}-nobal/erigon-data/logs/erigon.log" | tail -3

For longer comparisons, sample both logs at fixed intervals and aggregate (mean ± stdev) rather than eyeballing the tail.

Cleanup of Instance B only

NOBAL_DIR="${WORKDIR}-nobal"

docker stop "${DEVNET}-nobal-cl" 2>/dev/null || true
docker rm   "${DEVNET}-nobal-cl" 2>/dev/null || true

# Stop Instance B's erigon by PID (saved at start time) — avoids pkill -f regex risks.
if [ -f "$NOBAL_DIR/erigon.pid" ]; then
  PID=$(cat "$NOBAL_DIR/erigon.pid")
  kill "$PID" 2>/dev/null || true
  rm -f "$NOBAL_DIR/erigon.pid"
fi

# Optional — wipe Instance B's working directory.
# Refuse if WORKDIR is empty, NOBAL_DIR doesn't end with `-nobal`, or
# the directory doesn't carry the marker file we wrote at setup time.
# These guards prevent `rm -rf` from acting on an unrelated path if a
# variable is unset or has been overwritten.
if [ -n "$WORKDIR" ] \
    && [[ "$NOBAL_DIR" == *-nobal ]] \
    && [ -f "$NOBAL_DIR/devnet-info.txt" ] \
    && grep -q '^ignore_bal: true' "$NOBAL_DIR/devnet-info.txt"; then
  rm -rf "$NOBAL_DIR"
else
  echo "refusing to wipe '$NOBAL_DIR' — sanity check failed; clean it up by hand"
fi

Instance A is unaffected; use its own stop.sh / clean.sh to manage it.

Investigating discrepancies

If A and B disagree on block contents or state root (rather than just on throughput), this is not a BAL-vs-no-BAL throughput question — it's a correctness divergence. Stop the comparison and follow the failure-investigation flow in launch-devnet ("Investigating failures — finding the absolute truth"). The two instances are running the same erigon binary with one env-var difference, so a state-root diff between them points squarely at the BAL scheduling path.