perf(判题): 判题机上同时跑的程序从最多 8 个压到 4 个，挤的时候不再把不超时的判成超时

原来四道闸各管各的（worker 判题 2、api 试运行 2、提交前编译检查 2、worker 里流程图
评分的试运行又 2），api 和 worker 两个进程互相看不见，峰值 8 个程序压在服务器两个核上；
判题机按墙钟判超时，挤到一定程度会冤枉学生。

judge/slots.ts 在 Redis 里按池数名额（每个站点各数各的）：
- 后台池（正式判题、诊断重跑、流程图评分）上限 JUDGE_CONCURRENCY
- 交互池（运行例子、自己输入、生成测试点、编译检查）上限 TRIAL_CONCURRENCY
两池不互相借，正式判题排再长也挤不掉学生的「运行例子」。名额是带到期时间的租约，
进程被杀了到期自动作废；Redis 出错直接放行。正式判题的超时从拿到名额才开始算。

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/api/src/judge/run.ts

@@ -15,6 +15,7 @@ import type { JudgeJobData } from "./job"
 import { judgeConfigFor } from "./languages"
 import { isAccepted, JudgeStatus, type JudgeStatusValue } from "./status"
 import { parseProblemTemplate, shiftCompileLines } from "./template"
+import { withJudgeSlot } from "./slots"
 import { runSqlCase } from "./sql"
 import {
   nativeRuntimeError,
@@ -121,46 +122,22 @@ export async function postJudge(
  * 判题机只有 /judge 一个入口，得带一组测试点：给一组空输入，跑的那一下限 1 秒。
  * 判题机连不上、超时，一律当编得过 —— 那就和原来一样照常格式化。
  *
- * 这一下不进判题队列，所以自己排一道：同时最多 COMPILE_CHECK_CONCURRENCY 份在判题机上编，
- * 其余等着。服务器只有两核，不排的话一个班 40 人一起交 C++ 能把判题机挤到每人 8 秒超时，
- * 还拖慢正式判题。8 秒是连排队带编译的总预算，排不上也当编得过。
+ * 这一下不进判题队列，但和运行例子共用交互池的名额（judge/slots.ts）：服务器只有两核，
+ * 不排的话一个班 40 人一起交 C++ 能把判题机挤到每人 8 秒超时，还拖慢正式判题。
+ * 8 秒是连排队带编译的总预算，排不上也当编得过。
  */
-const COMPILE_CHECK_CONCURRENCY = 2
-let compileChecks = 0
-const compileCheckWaiting: (() => void)[] = []
-
 export async function compileFails(language: string, source: string) {
   const deadline = AbortSignal.timeout(8000)
-  if (compileChecks < COMPILE_CHECK_CONCURRENCY) {
-    compileChecks++
-  } else {
-    const admitted = await new Promise<boolean>((resolve) => {
-      const giveUp = () => {
-        compileCheckWaiting.splice(compileCheckWaiting.indexOf(wake), 1)
-        resolve(false)
-      }
-      const wake = () => {
-        deadline.removeEventListener("abort", giveUp)
-        resolve(true)
-      }
-      deadline.addEventListener("abort", giveUp, { once: true })
-      compileCheckWaiting.push(wake)
-    })
-    // 被叫醒时名额是直接转交过来的，compileChecks 不用再加
-    if (!admitted) return false
-  }
   try {
-    const response = await postJudge(language, source, 1000, 256, [{ input: "", output: "" }], {
-      signal: deadline,
+    return await withJudgeSlot("interactive", { holdMs: 30_000, signal: deadline }, async () => {
+      const response = await postJudge(language, source, 1000, 256, [{ input: "", output: "" }], {
+        signal: deadline,
+      })
+      const body = (await response.json()) as JudgeResponse
+      return body.err === "CompileError"
     })
-    const body = (await response.json()) as JudgeResponse
-    return body.err === "CompileError"
   } catch {
     return false
-  } finally {
-    const next = compileCheckWaiting.shift()
-    if (next) next()
-    else compileChecks--
   }
 }
 
@@ -210,13 +187,16 @@ async function requestJudge(
 ) {
   const timeoutMs = judgeTimeoutMs(timeLimit)
   try {
-    const response = await postJudge(language, code, timeLimit, memoryLimit, testCase, {
-      output,
-      signal: AbortSignal.timeout(timeoutMs),
+    // 超时从拿到名额才开始算：排队等名额不算判题机没回应
+    return await withJudgeSlot("judge", { holdMs: timeoutMs + 30_000 }, async () => {
+      const response = await postJudge(language, code, timeLimit, memoryLimit, testCase, {
+        output,
+        signal: AbortSignal.timeout(timeoutMs),
+      })
+      const body = await readCapped(response, MAX_RESPONSE_BYTES)
+      if (body === null) throw new Error("判题机返回的内容太大")
+      return JSON.parse(body) as JudgeResponse
     })
-    const body = await readCapped(response, MAX_RESPONSE_BYTES)
-    if (body === null) throw new Error("判题机返回的内容太大")
-    return JSON.parse(body) as JudgeResponse
   } catch (error) {
     // 这句会写进 err_info，学生能看到，别把 "The operation timed out." 原样给他
     if (error instanceof DOMException && error.name === "TimeoutError") {