This PR is a follow-up to the stale #32885.
Problem
ChainstateManager::IsInitialBlockDownload() currently acquires cs_main internally, even though most existing call sites already hold the lock. This becomes relevant for proposals like #34054, which would call IsInitialBlockDownload() from the scheduler thread without holding cs_main, potentially introducing lock contention.
Fix
Make ChainstateManager::IsInitialBlockDownload() lock-free by caching its result in a single atomic m_cached_is_ibd (true while in IBD, latched to false on exit).
Move the IBD exit checks out of IsInitialBlockDownload() (reader-side) into a new ChainstateManager::UpdateIBDStatus() (writer-side, called under cs_main).
Call UpdateIBDStatus() at strategic points where IBD exit conditions may change, after active chain tip updates in ConnectTip(), DisconnectTip(), and LoadChainTip(), and after ImportBlocks() returns.
With this, IsInitialBlockDownload() becomes a lock-free atomic read, avoiding internal cs_main acquisition on hot paths.
Testing and Benchmarks
This isn’t strictly an optimization (though some usecases might benefit from it), so rather as a sanity check I ran a reindex-chainstate and an AssumeUTXO load (without background validation).
0COMMITS="595504a43209bead162da54a204df7d140a25f0e 63e822b637f67242e3689adedc0155b34100e651"; \
1CC=gcc; CXX=g++; \
2BASE_DIR="/mnt/my_storage"; DATA_DIR="$BASE_DIR/ShallowBitcoinData"; LOG_DIR="$BASE_DIR/logs"; UTXO_SNAPSHOT_PATH="$BASE_DIR/utxo-910000.dat"; \
3(echo ""; for c in $COMMITS; do git fetch -q origin $c && git log -1 --pretty='%h %s' $c || exit 1; done; echo "") && \
4for DBCACHE in 4500; do \
5 (echo "assumeutxo load | 910000 blocks | dbcache ${DBCACHE} | $(hostname) | $(uname -m) | $(lscpu | grep 'Model name' | head -1 | cut -d: -f2 | xargs) | $(nproc) cores | $(free -h | awk '/^Mem:/{print $2}') RAM | $(df -T $BASE_DIR | awk 'NR==2{print $2}') | $(lsblk -no ROTA $(df --output=source $BASE_DIR | tail -1) | grep -q 0 && echo SSD || echo HDD)";) &&\
6 hyperfine \
7 --sort command \
8 --runs 3 \
9 --export-json "$BASE_DIR/assumeutxo-$(sed -E 's/(\w{8})\w+ ?/\1-/g;s/-$//'<<<"$COMMITS")-$DBCACHE-$CC-$(date +%s).json" \
10 --parameter-list COMMIT ${COMMITS// /,} \
11 --prepare "killall -9 bitcoind 2>/dev/null; rm -rf $DATA_DIR/blocks $DATA_DIR/chainstate $DATA_DIR/chainstate_snapshot $DATA_DIR/debug.log; git clean -fxd; git reset --hard {COMMIT} && \
12 cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=RelWithDebInfo && ninja -C build bitcoind bitcoin-cli -j2 && \
13 ./build/bin/bitcoind -datadir=$DATA_DIR -stopatheight=1 -printtoconsole=0; sleep 20 && \
14 ./build/bin/bitcoind -datadir=$DATA_DIR -daemon -blocksonly -connect=0 -dbcache=$DBCACHE -printtoconsole=0; sleep 20" \
15 --conclude "build/bin/bitcoin-cli -datadir=$DATA_DIR stop || true; killall bitcoind || true; sleep 10; \
16 echo '{COMMIT} | dbcache=$DBCACHE | chainstate: $(find $DATA_DIR/chainstate_snapshot -type f 2>/dev/null | wc -l) files, $(du -sb $DATA_DIR/chainstate_snapshot 2>/dev/null | cut -f1) bytes' >> $DATA_DIR/debug.log; \
17 cp $DATA_DIR/debug.log $LOG_DIR/debug-assumeutxo-{COMMIT}-dbcache-$DBCACHE-$(date +%s).log" \
18 "COMPILER=$CC DBCACHE=$DBCACHE ./build/bin/bitcoin-cli -datadir=$DATA_DIR -rpcclienttimeout=0 loadtxoutset $UTXO_SNAPSHOT_PATH"; \
19done
20
21595504a432 Merge bitcoin/bitcoin#34236: Add sedited to trusted-keys
2263e822b637 validation: make `IsInitialBlockDownload()` lock-free
23
24assumeutxo load | 910000 blocks | dbcache 4500 | i9-ssd | x86_64 | Intel(R) Core(TM) i9-9900K CPU @ 3.60GHz | 16 cores | 62Gi RAM | xfs | SSD
25
26Benchmark 1: COMPILER=gcc DBCACHE=4500 ./build/bin/bitcoin-cli -datadir=/mnt/my_storage/ShallowBitcoinData -rpcclienttimeout=0 loadtxoutset /mnt/my_storage/utxo-910000.dat (COMMIT = 595504a43209bead162da54a204df7d140a25f0e)
27 Time (mean ± σ): 418.452 s ± 0.461 s [User: 0.001 s, System: 0.001 s]
28 Range (min … max): 418.070 s … 418.964 s 3 runs
29
30Benchmark 2: COMPILER=gcc DBCACHE=4500 ./build/bin/bitcoin-cli -datadir=/mnt/my_storage/ShallowBitcoinData -rpcclienttimeout=0 loadtxoutset /mnt/my_storage/utxo-910000.dat (COMMIT = 63e822b637f67242e3689adedc0155b34100e651)
31 Time (mean ± σ): 415.994 s ± 0.294 s [User: 0.001 s, System: 0.001 s]
32 Range (min … max): 415.788 s … 416.330 s 3 runs
33
34Relative speed comparison
35 1.01 ± 0.00 COMPILER=gcc DBCACHE=4500 ./build/bin/bitcoin-cli -datadir=/mnt/my_storage/ShallowBitcoinData -rpcclienttimeout=0 loadtxoutset /mnt/my_storage/utxo-910000.dat (COMMIT = 595504a43209bead162da54a204df7d140a25f0e)
36 1.00 COMPILER=gcc DBCACHE=4500 ./build/bin/bitcoin-cli -datadir=/mnt/my_storage/ShallowBitcoinData -rpcclienttimeout=0 loadtxoutset /mnt/my_storage/utxo-910000.dat (COMMIT = 63e822b637f67242e3689adedc0155b34100e651)
0for DBCACHE in 4500; do \
1 COMMITS="595504a43209bead162da54a204df7d140a25f0e 63e822b637f67242e3689adedc0155b34100e651"; \
2 STOP=931139; CC=gcc; CXX=g++; \
3 BASE_DIR="/mnt/my_storage"; DATA_DIR="$BASE_DIR/BitcoinData"; LOG_DIR="$BASE_DIR/logs"; \
4 (echo ""; for c in $COMMITS; do git fetch -q origin $c && git log -1 --pretty='%h %s' $c || exit 1; done) && \
5 (echo "" && echo "$(date -I) | reindex-chainstate | ${STOP} blocks | dbcache ${DBCACHE} | $(hostname) | $(uname -m) | $(lscpu | grep 'Model name' | head -1 | cut -d: -f2 | xargs) | $(nproc) cores | $(free -h | awk '/^Mem:/{print $2}') RAM | SSD"; echo "") &&\
6 hyperfine \
7 --sort command \
8 --runs 1 \
9 --export-json "$BASE_DIR/rdx-$(sed -E 's/(\w{8})\w+ ?/\1-/g;s/-$//'<<<"$COMMITS")-$STOP-$DBCACHE-$CC.json" \
10 --parameter-list COMMIT ${COMMITS// /,} \
11 --prepare "killall -9 bitcoind 2>/dev/null; rm -f $DATA_DIR/debug.log; git clean -fxd; git reset --hard {COMMIT} && \
12 cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=Release -DENABLE_IPC=OFF && ninja -C build bitcoind -j1 && \
13 ./build/bin/bitcoind -datadir=$DATA_DIR -stopatheight=$STOP -dbcache=1000 -printtoconsole=0; sleep 20; rm -f $DATA_DIR/debug.log" \
14 --conclude "killall bitcoind || true; sleep 5; grep -q 'height=0' $DATA_DIR/debug.log && grep -q 'Disabling script verification at block [#1](/bitcoin-bitcoin/1/)' $DATA_DIR/debug.log && grep -q 'height=$STOP' $DATA_DIR/debug.log; \
15 cp $DATA_DIR/debug.log $LOG_DIR/debug-{COMMIT}-$(date +%s).log" \
16 "COMPILER=$CC ./build/bin/bitcoind -datadir=$DATA_DIR -stopatheight=$STOP -dbcache=$DBCACHE -reindex-chainstate -blocksonly -connect=0 -printtoconsole=0";
17done
18
19595504a432 Merge bitcoin/bitcoin#34236: Add sedited to trusted-keys
2063e822b637 validation: make `IsInitialBlockDownload()` lock-free
21
222026-01-12 | reindex-chainstate | 931139 blocks | dbcache 4500 | i9-ssd | x86_64 | Intel(R) Core(TM) i9-9900K CPU @ 3.60GHz | 16 cores | 62Gi RAM | SSD
23
24Benchmark 1: COMPILER=gcc ./build/bin/bitcoind -datadir=/mnt/my_storage/BitcoinData -stopatheight=931139 -dbcache=4500 -reindex-chainstate -blocksonly -connect=0 -printtoconsole=0 (COMMIT = 595504a43209bead162da54a204df7d140a25f0e)
25 Time (abs ≡): 17187.310 s [User: 33104.415 s, System: 937.548 s]
26
27Benchmark 2: COMPILER=gcc ./build/bin/bitcoind -datadir=/mnt/my_storage/BitcoinData -stopatheight=931139 -dbcache=4500 -reindex-chainstate -blocksonly -connect=0 -printtoconsole=0 (COMMIT = 63e822b637f67242e3689adedc0155b34100e651)
28 Time (abs ≡): 17240.300 s [User: 33164.803 s, System: 976.485 s]
29
30Relative speed comparison
31 1.00 COMPILER=gcc ./build/bin/bitcoind -datadir=/mnt/my_storage/BitcoinData -stopatheight=931139 -dbcache=4500 -reindex-chainstate -blocksonly -connect=0 -printtoconsole=0 (COMMIT = 595504a43209bead162da54a204df7d140a25f0e)
32 1.00 COMPILER=gcc ./build/bin/bitcoind -datadir=/mnt/my_storage/BitcoinData -stopatheight=931139 -dbcache=4500 -reindex-chainstate -blocksonly -connect=0 -printtoconsole=0 (COMMIT = 63e822b637f67242e3689adedc0155b34100e651)
