fix(gc): backfill new db records since snapshot epoch #5640
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hanabi1224
commented
May 12, 2025
| if let Err(e) = db.put_many_keyed(mem_db) { | ||
| tracing::warn!("{e}"); | ||
| } | ||
| tracing::info!( |
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Sample log from my laptop on mainnet:
2025-05-12T09:19:35.957856Z INFO forest::db::gc::snapshot: backfilled 57345 new db records since snapshot epoch, approximate heap size: 82.9 MiB, took 559ms 304us 167ns
…s-since-snapshot-epoch
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hanabi1224
requested review from
elmattic and
sudo-shashank
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a team
src/db/gc/snapshot.rs
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| if let Err(e) = self.reboot_tx.send(()) { | ||
| tracing::warn!("{e}"); | ||
| } | ||
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| *self.memory_db_head_key.write() = db.heaviest_tipset_key().ok(); | ||
| tokio::time::sleep(Duration::from_secs(1)).await; |
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Why 1s? Why do we need to sleep?
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This was to ensure write_ops_rx to be fully read but it was hacky. This commit refactors the logic and removes the sleep hack.
src/db/gc/snapshot.rs
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| // Backfill new db records during snapshot export | ||
| if let Ok(db) = open_db(self.db_root_dir.clone(), &self.db_config) { | ||
| if let Some(mem_db) = self.memory_db.write().take() { | ||
| let count = mem_db.len(); | ||
| let approximate_heap_size = { | ||
| let mut s = 0; | ||
| for (_k, v) in mem_db.iter() { | ||
| s += 64; | ||
| s += v.len(); | ||
| } | ||
| s | ||
| }; | ||
| let start = Instant::now(); | ||
| if let Err(e) = db.put_many_keyed(mem_db) { | ||
| tracing::warn!("{e}"); | ||
| } | ||
| tracing::info!( |
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Let's use more meaningful variable names. Especially the meaning of s is not clear.
src/db/gc/snapshot.rs
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| let approximate_heap_size = { | ||
| let mut s = 0; | ||
| for (_k, v) in mem_db.iter() { | ||
| s += 64; |
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That's the size of Cid
pub type Cid = CidGeneric<64>;There was a problem hiding this comment.
Actually, it's better to use std::mem::size_of::<Cid>()
src/db/gc/snapshot.rs
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| blessed_lite_snapshot: RwLock<Option<PathBuf>>, | ||
| db: RwLock<Option<Arc<DB>>>, | ||
| // On mainnet, it takes ~50MiB-100MiB RAM |
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maybe we can mention this in the gc guide also
…s-since-snapshot-epoch
sudo-shashank
approved these changes
May 22, 2025
LesnyRumcajs
approved these changes
May 22, 2025
…s-since-snapshot-epoch
LesnyRumcajs
approved these changes
May 23, 2025
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Summary of changes
This PR patches the snapshot GC to avoid losing db records that are inserted during snapshot export
Changes introduced in this pull request:
Reference issue to close (if applicable)
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Change checklist