R3944Realms/PlayerSync
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Optimize auto-save: snapshot on main thread, DB write on background

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Spark showed 5.66% server thread from auto-save DB writes blocking
the tick loop (~1-2ms per player per query, ~8 queries per save).

New approach:
- snapshotPlayerData() captures ALL entity data into an immutable
  PlayerDataSnapshot record on the main thread (fast, no DB I/O)
- writeSnapshotToDB() writes the snapshot to DB on the background
  thread via executorService (slow DB I/O off main thread)
- Mod data (Curios, Accessories, CosmeticArmor, NeoForge attachments)
  still read entity state on main thread but their DB writes happen
  inline (they manage their own connections)
- Sophisticated Backpacks/Storage/RS2 saves happen during snapshot
  phase on main thread (they need entity access for inventory scan)

Expected: ~60-70% reduction in main thread blocking from auto-save.

Vyrriox
This commit is contained in:
laforetbrut 2026-03-26 21:31:43 +01:00
parent d60b8eb01e
commit 1bf2a67e8d
1 changed files with 100 additions and 8 deletions
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108
src/main/java/vip/fubuki/playersync/sync/VanillaSync.java
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@ -970,6 +970,88 @@ public class VanillaSync {
}
}
/**
* Immutable snapshot of all player data, captured on the main thread.
* Can be safely passed to a background thread for DB writes.
*/
record PlayerDataSnapshot(
String uuid, int xp, int score, int foodLevel, int health,
String leftHand, String cursors,
String equipment, String inventory, String enderChest, String effects,
String advancements,
// Mod data snapshots (serialized strings, thread-safe)
String curiosData, String accessoriesData, String cosmeticArmorData, String attachmentsData
) {}
/**
* Captures all player data into an immutable snapshot on the MAIN THREAD.
* This is fast (no DB I/O, just serialization to strings).
*/
private static PlayerDataSnapshot snapshotPlayerData(Player player) throws Exception {
String uuid = player.getUUID().toString();
int XP = getTotalExperience(player);
int score = player.getScore();
int foodLevel = player.getFoodData().getFoodLevel();
int health = (int) player.getHealth();
String leftHand = getNbtForStorage(player.getItemInHand(net.minecraft.world.InteractionHand.OFF_HAND));
String cursors = getNbtForStorage(player.containerMenu.getCarried());
Map<Integer, String> equipmentMap = new HashMap<>();
for (int i = 0; i < player.getInventory().armor.size(); i++) {
equipmentMap.put(i, getNbtForStorage(player.getInventory().armor.get(i)));
}
Map<Integer, String> inventoryMap = new HashMap<>();
for (int i = 0; i < player.getInventory().items.size(); i++) {
inventoryMap.put(i, getNbtForStorage(player.getInventory().items.get(i)));
}
Map<Integer, String> enderChestMap = new HashMap<>();
for (int i = 0; i < player.getEnderChestInventory().getContainerSize(); i++) {
enderChestMap.put(i, getNbtForStorage(player.getEnderChestInventory().getItem(i)));
}
Map<Integer, String> effectMap = new HashMap<>();
for (Map.Entry<Holder<MobEffect>, MobEffectInstance> entry : player.getActiveEffectsMap().entrySet()) {
Tag effectTag = entry.getValue().save();
effectMap.put(BuiltInRegistries.MOB_EFFECT.getId(entry.getKey().value()), serialize(effectTag.toString()));
}
// Advancements (file read, fast)
String advancements = "";
if (JdbcConfig.SYNC_ADVANCEMENTS.get() && player instanceof ServerPlayer sp) {
try { sp.getAdvancements().save(); } catch (Exception ignored) {}
Path path = sp.getServer().getServerDirectory().resolve(getSyncWorldForServer());
File advFile = new File(path.toFile(), "/advancements/" + uuid + ".json");
if (advFile.exists()) {
advancements = new String(Files.readAllBytes(advFile.toPath()), StandardCharsets.UTF_8);
}
}
// Mod data snapshots - also on main thread (reads entity state safely)
// Sophisticated Backpacks/Storage/RS2 are saved via their own store methods
if (ModList.get().isLoaded("sophisticatedbackpacks")) ModsSupport.storeSophisticatedBackpacks(player);
if (ModList.get().isLoaded("sophisticatedstorage")) ModsSupport.storeSophisticatedStorageItems(player);
if (ModList.get().isLoaded("refinedstorage")) ModsSupport.storeRefinedStorageDisks(player);
return new PlayerDataSnapshot(
uuid, XP, score, foodLevel, health,
leftHand, cursors,
equipmentMap.toString(), inventoryMap.toString(), enderChestMap.toString(), effectMap.toString(),
advancements,
null, null, null, null // Curios/Accessories/CosmeticArmor/Attachments handled by their own DB writes
);
}
/**
* Writes a snapshot to the DB. Runs on BACKGROUND THREAD (no entity access).
*/
private static void writeSnapshotToDB(PlayerDataSnapshot s) throws Exception {
JDBCsetUp.executePreparedUpdate(
"UPDATE player_data SET inventory=?, armor=?, xp=?, effects=?, enderchest=?, score=?, food_level=?, health=?, advancements=?, left_hand=?, cursors=? WHERE uuid=?",
s.inventory(), s.equipment(), s.xp(), s.effects(), s.enderChest(), s.score(), s.foodLevel(), s.health(), s.advancements(), s.leftHand(), s.cursors(), s.uuid());
// Curios, Accessories, CosmeticArmor, Attachments are already written by their own store methods
// during the snapshot phase (they do their own DB writes internally)
}
private static String getSyncWorldForServer() {
if (!JdbcConfig.SYNC_WORLD.get().isEmpty()) {
PlayerSync.LOGGER.warn("Using configuration 'sync_world' on servers is deprecated. Please leave the array empty. Falling back to first entry.");
@ -1028,11 +1110,9 @@ public class VanillaSync {
});
}
// Auto-save all online players
// FIX C-1/C-2/C-4: onServerTick runs on the MAIN THREAD. We call store() and mod saves
// directly here to safely read entity state (inventory, curios, effects, etc.).
// The DB writes inside store() block briefly (~1-5ms per player) but this is acceptable
// for a 60-second interval. This eliminates all off-thread entity access duplication exploits.
// Auto-save: Snapshot entity data on MAIN THREAD (fast), then write to DB on BACKGROUND THREAD.
// Previously, store() ran entirely on main thread including DB writes, blocking the tick loop
// for ~5ms per player per save (~5.66% server thread usage from Spark profiling).
if (autoSaveTickCounter >= AUTO_SAVE_INTERVAL_TICKS) {
autoSaveTickCounter = 0;
MinecraftServer server = ServerLifecycleHooks.getCurrentServer();
@ -1043,17 +1123,29 @@ public class VanillaSync {
}
String puuid = player.getUUID().toString();
ReentrantLock lock = getPlayerLock(puuid);
if (!lock.tryLock()) continue; // Skip if already being saved (logout in progress)
if (!lock.tryLock()) continue;
try {
store(player, false);
// === MAIN THREAD: Snapshot entity data + mod data (reads are fast) ===
final PlayerDataSnapshot snapshot = snapshotPlayerData(player);
// Curios/Accessories/CosmeticArmor/Attachments have their own DB writes internally,
// but they READ entity state here on the main thread (safe)
if (ModList.get().isLoaded("curios") && !player.isDeadOrDying()) {
new ModsSupport().StoreCurios(player, false);
}
if (!player.isDeadOrDying()) {
ModCompatSync.storeAll(player);
}
// === BACKGROUND THREAD: Write main snapshot to DB (slow, off main thread) ===
executorService.submit(() -> {
try {
writeSnapshotToDB(snapshot);
} catch (Exception e) {
PlayerSync.LOGGER.error("Error auto-saving player {}", puuid, e);
}
});
} catch (Exception e) {
PlayerSync.LOGGER.error("Error auto-saving player {}", player.getUUID(), e);
PlayerSync.LOGGER.error("Error snapshotting player {}", puuid, e);
} finally {
lock.unlock();
}