garbage collect not commited tries

core/blockchain.go

@@ -1451,7 +1451,8 @@ func (bc *BlockChain) writeBlockWithState(block *types.Block, receipts []*types.
 	// If MaxNumberOfBlocksToSkipStateSaving or MaxAmountOfGasToSkipStateSaving is not zero, then flushing of some blocks will be skipped:
 	// * at most MaxNumberOfBlocksToSkipStateSaving block state commits will be skipped
 	// * sum of gas used in skipped blocks will be at most MaxAmountOfGasToSkipStateSaving
-	if bc.cacheConfig.TrieDirtyDisabled {
+	archiveNode := bc.cacheConfig.TrieDirtyDisabled
+	if archiveNode {
 		var maySkipCommiting, blockLimitReached, gasLimitReached bool
 		if bc.cacheConfig.MaxNumberOfBlocksToSkipStateSaving != 0 {
 			maySkipCommiting = true
@@ -1474,10 +1475,10 @@ func (bc *BlockChain) writeBlockWithState(block *types.Block, receipts []*types.
 			bc.amountOfGasInBlocksToSkipStateSaving = bc.cacheConfig.MaxAmountOfGasToSkipStateSaving
 			return bc.triedb.Commit(root, false)
 		}
-		return nil
+		// we are skipping saving the trie to diskdb, so we need to keep the trie in memory and garbage collect it later
 	}
 
-	// Full but not archive node, do proper garbage collection
+	// Full node or archive node that's not keeping all states, do proper garbage collection
 	bc.triedb.Reference(root, common.Hash{}) // metadata reference to keep trie alive
 	bc.triegc.Push(trieGcEntry{root, block.Header().Time}, -int64(block.NumberU64()))
 
@@ -1510,7 +1511,8 @@ func (bc *BlockChain) writeBlockWithState(block *types.Block, receipts []*types.
 		}
 		flushInterval := time.Duration(bc.flushInterval.Load())
 		// If we exceeded out time allowance, flush an entire trie to disk
-		if bc.gcproc > flushInterval && prevEntry != nil {
+		// In case of archive node that skips some trie commits we don't flush tries here
+		if bc.gcproc > flushInterval && prevEntry != nil && !archiveNode {
 			// If the header is missing (canonical chain behind), we're reorging a low
 			// diff sidechain. Suspend committing until this operation is completed.
 			header := bc.GetHeaderByNumber(prevNum)