fix(backend): memory leak in memory caches (misskey-dev#14363)

cherry picked from commit bf8c42e

Co-authored-by: かっこかり <[email protected]>
Co-authored-by: Hazel K <[email protected]>

packages/backend/src/core/AvatarDecorationService.ts

@@ -29,7 +29,7 @@ export class AvatarDecorationService implements OnApplicationShutdown {
 		private moderationLogService: ModerationLogService,
 		private globalEventService: GlobalEventService,
 	) {
-		this.cache = new MemorySingleCache<MiAvatarDecoration[]>(1000 * 60 * 30);
+		this.cache = new MemorySingleCache<MiAvatarDecoration[]>(1000 * 60 * 30); // 30s
 
 		this.redisForSub.on('message', this.onMessage);
 	}

packages/backend/src/core/CacheService.ts

@@ -56,10 +56,10 @@ export class CacheService implements OnApplicationShutdown {
 	) {
 		//this.onMessage = this.onMessage.bind(this);
 
-		this.userByIdCache = new MemoryKVCache<MiUser>(Infinity);
-		this.localUserByNativeTokenCache = new MemoryKVCache<MiLocalUser | null>(Infinity);
-		this.localUserByIdCache = new MemoryKVCache<MiLocalUser>(Infinity);
-		this.uriPersonCache = new MemoryKVCache<MiUser | null>(Infinity);
+		this.userByIdCache = new MemoryKVCache<MiUser>(1000 * 60 * 5); // 5m
+		this.localUserByNativeTokenCache = new MemoryKVCache<MiLocalUser | null>(1000 * 60 * 5); // 5m
+		this.localUserByIdCache = new MemoryKVCache<MiLocalUser>(1000 * 60 * 5); // 5m
+		this.uriPersonCache = new MemoryKVCache<MiUser | null>(1000 * 60 * 5); // 5m
 
 		this.userProfileCache = new RedisKVCache<MiUserProfile>(this.redisClient, 'userProfile', {
 			lifetime: 1000 * 60 * 30, // 30m
@@ -135,14 +135,14 @@ export class CacheService implements OnApplicationShutdown {
 					if (user == null) {
 						this.userByIdCache.delete(body.id);
 						this.localUserByIdCache.delete(body.id);
-						for (const [k, v] of this.uriPersonCache.cache.entries()) {
+						for (const [k, v] of this.uriPersonCache.entries) {
 							if (v.value?.id === body.id) {
 								this.uriPersonCache.delete(k);
 							}
 						}
 					} else {
 						this.userByIdCache.set(user.id, user);
-						for (const [k, v] of this.uriPersonCache.cache.entries()) {
+						for (const [k, v] of this.uriPersonCache.entries) {
 							if (v.value?.id === user.id) {
 								this.uriPersonCache.set(k, user);
 							}

packages/backend/src/core/CustomEmojiService.ts

@@ -24,7 +24,7 @@ const parseEmojiStrRegexp = /^([-\w]+)(?:@([\w.-]+))?$/;
 
 @Injectable()
 export class CustomEmojiService implements OnApplicationShutdown {
-	private cache: MemoryKVCache<MiEmoji | null>;
+	private emojisCache: MemoryKVCache<MiEmoji | null>;
 	public localEmojisCache: RedisSingleCache<Map<string, MiEmoji>>;
 
 	constructor(
@@ -40,7 +40,7 @@ export class CustomEmojiService implements OnApplicationShutdown {
 		private moderationLogService: ModerationLogService,
 		private globalEventService: GlobalEventService,
 	) {
-		this.cache = new MemoryKVCache<MiEmoji | null>(1000 * 60 * 60 * 12);
+		this.emojisCache = new MemoryKVCache<MiEmoji | null>(1000 * 60 * 60 * 12); // 12h
 
 		this.localEmojisCache = new RedisSingleCache<Map<string, MiEmoji>>(this.redisClient, 'localEmojis', {
 			lifetime: 1000 * 60 * 30, // 30m
@@ -346,7 +346,7 @@ export class CustomEmojiService implements OnApplicationShutdown {
 			host,
 		})) ?? null;
 
-		const emoji = await this.cache.fetch(`${name} ${host}`, queryOrNull);
+		const emoji = await this.emojisCache.fetch(`${name} ${host}`, queryOrNull);
 
 		if (emoji == null) return null;
 		return emoji.publicUrl || emoji.originalUrl; // || emoji.originalUrl してるのは後方互換性のため（publicUrlはstringなので??はだめ）
@@ -372,7 +372,7 @@ export class CustomEmojiService implements OnApplicationShutdown {
 	 */
 	@bindThis
 	public async prefetchEmojis(emojis: { name: string; host: string | null; }[]): Promise<void> {
-		const notCachedEmojis = emojis.filter(emoji => this.cache.get(`${emoji.name} ${emoji.host}`) == null);
+		const notCachedEmojis = emojis.filter(emoji => this.emojisCache.get(`${emoji.name} ${emoji.host}`) == null);
 		const emojisQuery: any[] = [];
 		const hosts = new Set(notCachedEmojis.map(e => e.host));
 		for (const host of hosts) {
@@ -387,7 +387,7 @@ export class CustomEmojiService implements OnApplicationShutdown {
 			select: ['name', 'host', 'originalUrl', 'publicUrl'],
 		}) : [];
 		for (const emoji of _emojis) {
-			this.cache.set(`${emoji.name} ${emoji.host}`, emoji);
+			this.emojisCache.set(`${emoji.name} ${emoji.host}`, emoji);
 		}
 	}
 
@@ -412,7 +412,7 @@ export class CustomEmojiService implements OnApplicationShutdown {
 
 	@bindThis
 	public dispose(): void {
-		this.cache.dispose();
+		this.emojisCache.dispose();
 	}
 
 	@bindThis

packages/backend/src/core/RelayService.ts

@@ -35,7 +35,7 @@ export class RelayService {
 		private createSystemUserService: CreateSystemUserService,
 		private apRendererService: ApRendererService,
 	) {
-		this.relaysCache = new MemorySingleCache<MiRelay[]>(1000 * 60 * 10);
+		this.relaysCache = new MemorySingleCache<MiRelay[]>(1000 * 60 * 10); // 10m
 	}
 
 	@bindThis

packages/backend/src/core/RoleService.ts

@@ -149,10 +149,8 @@ export class RoleService implements OnApplicationShutdown, OnModuleInit {
 		private moderationLogService: ModerationLogService,
 		private fanoutTimelineService: FanoutTimelineService,
 	) {
-		//this.onMessage = this.onMessage.bind(this);
-
-		this.rolesCache = new MemorySingleCache<MiRole[]>(1000 * 60 * 60 * 1);
-		this.roleAssignmentByUserIdCache = new MemoryKVCache<MiRoleAssignment[]>(1000 * 60 * 60 * 1);
+		this.rolesCache = new MemorySingleCache<MiRole[]>(1000 * 60 * 60); // 1h
+		this.roleAssignmentByUserIdCache = new MemoryKVCache<MiRoleAssignment[]>(1000 * 60 * 5); // 5m
 
 		this.redisForSub.on('message', this.onMessage);
 	}

packages/backend/src/core/UserKeypairService.ts

@@ -25,7 +25,7 @@ export class UserKeypairService implements OnApplicationShutdown {
 	) {
 		this.cache = new RedisKVCache<MiUserKeypair>(this.redisClient, 'userKeypair', {
 			lifetime: 1000 * 60 * 60 * 24, // 24h
-			memoryCacheLifetime: Infinity,
+			memoryCacheLifetime: 1000 * 60 * 60, // 1h
 			fetcher: (key) => this.userKeypairsRepository.findOneByOrFail({ userId: key }),
 			toRedisConverter: (value) => JSON.stringify(value),
 			fromRedisConverter: (value) => JSON.parse(value),

packages/backend/src/core/activitypub/ApDbResolverService.ts

@@ -54,8 +54,8 @@ export class ApDbResolverService implements OnApplicationShutdown {
 		private cacheService: CacheService,
 		private apPersonService: ApPersonService,
 	) {
-		this.publicKeyCache = new MemoryKVCache<MiUserPublickey | null>(Infinity);
-		this.publicKeyByUserIdCache = new MemoryKVCache<MiUserPublickey | null>(Infinity);
+		this.publicKeyCache = new MemoryKVCache<MiUserPublickey | null>(1000 * 60 * 60 * 12); // 12h
+		this.publicKeyByUserIdCache = new MemoryKVCache<MiUserPublickey | null>(1000 * 60 * 60 * 12); // 12h
 	}
 
 	@bindThis

packages/backend/src/misc/cache.ts

@@ -7,23 +7,23 @@ import * as Redis from 'ioredis';
 import { bindThis } from '@/decorators.js';
 
 export class RedisKVCache<T> {
-	private redisClient: Redis.Redis;
-	private name: string;
-	private lifetime: number;
-	private memoryCache: MemoryKVCache<T>;
-	private fetcher: (key: string) => Promise<T>;
-	private toRedisConverter: (value: T) => string;
-	private fromRedisConverter: (value: string) => T | undefined;
-
-	constructor(redisClient: RedisKVCache<T>['redisClient'], name: RedisKVCache<T>['name'], opts: {
-		lifetime: RedisKVCache<T>['lifetime'];
-		memoryCacheLifetime: number;
-		fetcher: RedisKVCache<T>['fetcher'];
-		toRedisConverter: RedisKVCache<T>['toRedisConverter'];
-		fromRedisConverter: RedisKVCache<T>['fromRedisConverter'];
-	}) {
-		this.redisClient = redisClient;
-		this.name = name;
+	private readonly lifetime: number;
+	private readonly memoryCache: MemoryKVCache<T>;
+	private readonly fetcher: (key: string) => Promise<T>;
+	private readonly toRedisConverter: (value: T) => string;
+	private readonly fromRedisConverter: (value: string) => T | undefined;
+
+	constructor(
+		private redisClient: Redis.Redis,
+		private name: string,
+		opts: {
+			lifetime: RedisKVCache<T>['lifetime'];
+			memoryCacheLifetime: number;
+			fetcher: RedisKVCache<T>['fetcher'];
+			toRedisConverter: RedisKVCache<T>['toRedisConverter'];
+			fromRedisConverter: RedisKVCache<T>['fromRedisConverter'];
+		},
+	) {
 		this.lifetime = opts.lifetime;
 		this.memoryCache = new MemoryKVCache(opts.memoryCacheLifetime);
 		this.fetcher = opts.fetcher;
@@ -55,10 +55,13 @@ export class RedisKVCache<T> {
 
 		const cached = await this.redisClient.get(`kvcache:${this.name}:${key}`);
 		if (cached == null) return undefined;
-		const parsed = this.fromRedisConverter(cached);
-		if (parsed == null) return undefined;
-		this.memoryCache.set(key, parsed);
-		return parsed;
+
+		const value = this.fromRedisConverter(cached);
+		if (value !== undefined) {
+			this.memoryCache.set(key, value);
+		}
+
+		return value;
 	}
 
 	@bindThis
@@ -69,6 +72,10 @@ export class RedisKVCache<T> {
 
 	/**
 	 * キャッシュがあればそれを返し、無ければfetcherを呼び出して結果をキャッシュ&返します
+	 * This awaits the call to Redis to ensure that the write succeeded, which is important for a few reasons:
+	 *   * Other code uses this to synchronize changes between worker processes. A failed write can internally de-sync the cluster.
+	 *   * Without an `await`, consecutive calls could race. An unlucky race could result in the older write overwriting the newer value.
+	 *   * Not awaiting here makes the entire cache non-consistent. The prevents many possible uses.
 	 */
 	@bindThis
 	public async fetch(key: string): Promise<T> {
@@ -80,14 +87,14 @@ export class RedisKVCache<T> {
 
 		// Cache MISS
 		const value = await this.fetcher(key);
-		this.set(key, value);
+		await this.set(key, value);
 		return value;
 	}
 
 	@bindThis
 	public async refresh(key: string) {
 		const value = await this.fetcher(key);
-		this.set(key, value);
+		await this.set(key, value);
 
 		// TODO: イベント発行して他プロセスのメモリキャッシュも更新できるようにする
 	}
@@ -104,23 +111,23 @@ export class RedisKVCache<T> {
 }
 
 export class RedisSingleCache<T> {
-	private redisClient: Redis.Redis;
-	private name: string;
-	private lifetime: number;
-	private memoryCache: MemorySingleCache<T>;
-	private fetcher: () => Promise<T>;
-	private toRedisConverter: (value: T) => string;
-	private fromRedisConverter: (value: string) => T | undefined;
-
-	constructor(redisClient: RedisSingleCache<T>['redisClient'], name: RedisSingleCache<T>['name'], opts: {
-		lifetime: RedisSingleCache<T>['lifetime'];
-		memoryCacheLifetime: number;
-		fetcher: RedisSingleCache<T>['fetcher'];
-		toRedisConverter: RedisSingleCache<T>['toRedisConverter'];
-		fromRedisConverter: RedisSingleCache<T>['fromRedisConverter'];
-	}) {
-		this.redisClient = redisClient;
-		this.name = name;
+	private readonly lifetime: number;
+	private readonly memoryCache: MemorySingleCache<T>;
+	private readonly fetcher: () => Promise<T>;
+	private readonly toRedisConverter: (value: T) => string;
+	private readonly fromRedisConverter: (value: string) => T | undefined;
+
+	constructor(
+		private redisClient: Redis.Redis,
+		private name: string,
+		opts: {
+			lifetime: number;
+			memoryCacheLifetime: number;
+			fetcher: RedisSingleCache<T>['fetcher'];
+			toRedisConverter: RedisSingleCache<T>['toRedisConverter'];
+			fromRedisConverter: RedisSingleCache<T>['fromRedisConverter'];
+		},
+	) {
 		this.lifetime = opts.lifetime;
 		this.memoryCache = new MemorySingleCache(opts.memoryCacheLifetime);
 		this.fetcher = opts.fetcher;
@@ -152,10 +159,13 @@ export class RedisSingleCache<T> {
 
 		const cached = await this.redisClient.get(`singlecache:${this.name}`);
 		if (cached == null) return undefined;
-		const parsed = this.fromRedisConverter(cached);
-		if (parsed == null) return undefined;
-		this.memoryCache.set(parsed);
-		return parsed;
+
+		const value = this.fromRedisConverter(cached);
+		if (value !== undefined) {
+			this.memoryCache.set(value);
+		}
+
+		return value;
 	}
 
 	@bindThis
@@ -166,6 +176,10 @@ export class RedisSingleCache<T> {
 
 	/**
 	 * キャッシュがあればそれを返し、無ければfetcherを呼び出して結果をキャッシュ&返します
+	 * This awaits the call to Redis to ensure that the write succeeded, which is important for a few reasons:
+	 *   * Other code uses this to synchronize changes between worker processes. A failed write can internally de-sync the cluster.
+	 *   * Without an `await`, consecutive calls could race. An unlucky race could result in the older write overwriting the newer value.
+	 *   * Not awaiting here makes the entire cache non-consistent. The prevents many possible uses.
 	 */
 	@bindThis
 	public async fetch(): Promise<T> {
@@ -177,14 +191,14 @@ export class RedisSingleCache<T> {
 
 		// Cache MISS
 		const value = await this.fetcher();
-		this.set(value);
+		await this.set(value);
 		return value;
 	}
 
 	@bindThis
 	public async refresh() {
 		const value = await this.fetcher();
-		this.set(value);
+		await this.set(value);
 
 		// TODO: イベント発行して他プロセスのメモリキャッシュも更新できるようにする
 	}
@@ -197,18 +211,12 @@ export class MemoryKVCache<T> {
 	 * データを持つマップ
 	 * これを直接操作するべきではない
 	 */
-	public cache: Map<string, { date: number; value: T; }>;
-	private lifetime: number;
-	private gcIntervalHandle: NodeJS.Timeout;
-
-	constructor(lifetime: MemoryKVCache<never>['lifetime']) {
-		this.cache = new Map();
-		this.lifetime = lifetime;
+	private readonly cache = new Map<string, { date: number; value: T; }>();
+	private readonly gcIntervalHandle = setInterval(() => this.gc(), 1000 * 60 * 3); // 3m
 
-		this.gcIntervalHandle = setInterval(() => {
-			this.gc();
-		}, 1000 * 60 * 3);
-	}
+	constructor(
+		private readonly lifetime: number,
+	) {}
 
 	@bindThis
 	/**
@@ -293,27 +301,34 @@ export class MemoryKVCache<T> {
 	@bindThis
 	public gc(): void {
 		const now = Date.now();
+
 		for (const [key, { date }] of this.cache.entries()) {
-			if ((now - date) > this.lifetime) {
-				this.cache.delete(key);
-			}
+			// The map is ordered from oldest to youngest.
+			// We can stop once we find an entry that's still active, because all following entries must *also* be active.
+			const age = now - date;
+			if (age < this.lifetime) break;
+
+			this.cache.delete(key);
 		}
 	}
 
 	@bindThis
 	public dispose(): void {
 		clearInterval(this.gcIntervalHandle);
 	}
+
+	public get entries() {
+		return this.cache.entries();
+	}
 }
 
 export class MemorySingleCache<T> {
 	private cachedAt: number | null = null;
 	private value: T | undefined;
-	private lifetime: number;
 
-	constructor(lifetime: MemorySingleCache<never>['lifetime']) {
-		this.lifetime = lifetime;
-	}
+	constructor(
+		private lifetime: number,
+	) {}
 
 	@bindThis
 	public set(value: T): void {

packages/backend/src/queue/processors/DeliverProcessorService.ts

@@ -44,7 +44,7 @@ export class DeliverProcessorService {
 		private queueLoggerService: QueueLoggerService,
 	) {
 		this.logger = this.queueLoggerService.logger.createSubLogger('deliver');
-		this.suspendedHostsCache = new MemorySingleCache<MiInstance[]>(1000 * 60 * 60);
+		this.suspendedHostsCache = new MemorySingleCache<MiInstance[]>(1000 * 60 * 60); // 1h
 	}
 
 	@bindThis

packages/backend/src/server/NodeinfoServerService.ts

@@ -133,7 +133,7 @@ export class NodeinfoServerService {
 			return document;
 		};
 
-		const cache = new MemorySingleCache<Awaited<ReturnType<typeof nodeinfo2>>>(1000 * 60 * 10);
+		const cache = new MemorySingleCache<Awaited<ReturnType<typeof nodeinfo2>>>(1000 * 60 * 10); // 10m
 
 		fastify.get(nodeinfo2_1path, async (request, reply) => {
 			const base = await cache.fetch(() => nodeinfo2(21));