# Dockerfile - LD_PRELOAD 方式
FROM ubuntu:22.04

RUN apt-get update && apt-get install -y \
    libjemalloc2 \
    && rm -rf /var/lib/apt/lists/*

# 设置 LD_PRELOAD
ENV LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libjemalloc.so.2
ENV MALLOC_CONF="narenas:4,dirty_decay_ms:3000,background_thread:true"

COPY my_server /usr/local/bin/
CMD ["my_server"]

# Dockerfile - 编译时链接
FROM ubuntu:22.04 AS builder

RUN apt-get update && apt-get install -y \
    build-essential \
    libjemalloc-dev \
    && rm -rf /var/lib/apt/lists/*

WORKDIR /build
COPY . .
RUN gcc -O2 -g -o my_server main.c -ljemalloc -lpthread

# 运行镜像
FROM ubuntu:22.04

RUN apt-get update && apt-get install -y \
    libjemalloc2 \
    && rm -rf /var/lib/apt/lists/*

COPY --from=builder /build/my_server /usr/local/bin/

# 即使编译时链接了，也可以通过 LD_PRELOAD 调整配置
ENV MALLOC_CONF="narenas:4,dirty_decay_ms:3000,background_thread:true"

CMD ["my_server"]

# Dockerfile - 从源码编译 jemalloc
FROM ubuntu:22.04 AS jemalloc-builder

RUN apt-get update && apt-get install -y \
    build-essential autoconf automake libtool \
    && rm -rf /var/lib/apt/lists/*

RUN wget https://github.com/jemalloc/jemalloc/releases/download/5.3.0/jemalloc-5.3.0.tar.bz2 \
    && tar xjf jemalloc-5.3.0.tar.bz2 \
    && cd jemalloc-5.3.0 \
    && ./configure \
        --prefix=/opt/jemalloc \
        --enable-prof \
        --enable-stats \
        --with-malloc_conf="narenas:8,dirty_decay_ms:3000,background_thread:true" \
    && make -j$(nproc) \
    && make install

# 应用构建
FROM ubuntu:22.04 AS app-builder

RUN apt-get update && apt-get install -y build-essential && rm -rf /var/lib/apt/lists/*
COPY --from=jemalloc-builder /opt/jemalloc /opt/jemalloc
ENV PKG_CONFIG_PATH=/opt/jemalloc/lib/pkgconfig

WORKDIR /build
COPY . .
RUN gcc -O2 -g -o my_server main.c \
    -I/opt/jemalloc/include \
    -L/opt/jemalloc/lib \
    -Wl,-rpath,/opt/jemalloc/lib \
    -ljemalloc -lpthread

# 最终运行镜像
FROM ubuntu:22.04

COPY --from=jemalloc-builder /opt/jemalloc /opt/jemalloc
COPY --from=app-builder /build/my_server /usr/local/bin/

ENV LD_LIBRARY_PATH=/opt/jemalloc/lib
ENV LD_PRELOAD=/opt/jemalloc/lib/libjemalloc.so.2
ENV MALLOC_CONF="prof:true,prof_active:true,prof_prefix:/tmp/jeprof,narenas:8,background_thread:true"

CMD ["my_server"]

# Dockerfile.redis - 带 jemalloc profiling 的 Redis
FROM redis:7.0-alpine

# Alpine 使用 musl，需要安装 jemalloc
RUN apk add --no-cache jemalloc

ENV LD_PRELOAD=/usr/lib/libjemalloc.so.2
ENV MALLOC_CONF="narenas:4,dirty_decay_ms:3000,background_thread:true"

EXPOSE 6379
CMD ["redis-server", "/etc/redis/redis.conf"]

# docker-compose.yml
version: '3.8'
services:
  redis:
    build:
      context: .
      dockerfile: Dockerfile.redis
    ports:
      - "6379:6379"
    volumes:
      - redis-data:/data
      - ./redis.conf:/etc/redis/redis.conf
      - /tmp/jeprof:/tmp/jeprof   # profile 输出
    deploy:
      resources:
        limits:
          memory: 2G
        reservations:
          memory: 1G
    environment:
      - MALLOC_CONF=narenas:4,dirty_decay_ms:2000,background_thread:true,prof:true,prof_active:true,prof_prefix:/tmp/jeprof

volumes:
  redis-data:

# 容器优化配置
MALLOC_CONF="\
narenas:4,\
dirty_decay_ms:1000,\
muzzy_decay_ms:3000,\
background_thread:true,\
tcache_max:32768"

# 查看 cgroup 内存限制
cat /sys/fs/cgroup/memory/memory.limit_in_bytes  # cgroup v1
cat /sys/fs/cgroup/memory.max                      # cgroup v2

# 查看进程实际 RSS
cat /proc/self/status | grep VmRSS

# 查看 cgroup 统计的内存使用
cat /sys/fs/cgroup/memory/memory.usage_in_bytes    # cgroup v1
cat /sys/fs/cgroup/memory.current                   # cgroup v2

# 监控 OOM 事件
dmesg | grep -i oom
journalctl -k | grep -i oom

# 在容器内查看内存压力
cat /proc/pressure/memory

# Kubernetes Pod 配置
apiVersion: v1
kind: Pod
metadata:
  name: my-app
spec:
  containers:
  - name: app
    image: my-app:latest
    env:
    - name: LD_PRELOAD
      value: "/usr/lib/x86_64-linux-gnu/libjemalloc.so.2"
    - name: MALLOC_CONF
      value: "narenas:4,dirty_decay_ms:2000,background_thread:true,stats_print:true"
    volumeMounts:
    - name: jeprof
      mountPath: /tmp/jeprof
  - name: profiler
    image: busybox
    command: ["sh", "-c", "while true; do sleep 300; ls -la /tmp/jeprof/; done"]
    volumeMounts:
    - name: jeprof
      mountPath: /tmp/jeprof
  volumes:
  - name: jeprof
    emptyDir: {}

// jemalloc_metrics.c - 导出 jemalloc 指标到 HTTP 端点
#include <jemalloc/jemalloc.h>
#include <stdio.h>
#include <string.h>

// 读取 jemalloc 统计指标
typedef struct {
    size_t allocated;
    size_t active;
    size_t metadata;
    size_t resident;
    size_t mapped;
} jemalloc_stats_t;

void get_jemalloc_stats(jemalloc_stats_t *stats) {
    uint64_t epoch = 1;
    size_t sz = sizeof(epoch);
    je_mallctl("epoch", &epoch, &sz, &epoch, sz);

    sz = sizeof(size_t);
    je_mallctl("stats.allocated", &stats->allocated, &sz, NULL, 0);
    je_mallctl("stats.active",    &stats->active,    &sz, NULL, 0);
    je_mallctl("stats.metadata",  &stats->metadata,  &sz, NULL, 0);
    je_mallctl("stats.resident",  &stats->resident,  &sz, NULL, 0);
    je_mallctl("stats.mapped",    &stats->mapped,    &sz, NULL, 0);
}

// 生成 Prometheus 格式指标
void print_prometheus_metrics(FILE *fp) {
    jemalloc_stats_t s;
    get_jemalloc_stats(&s);

    fprintf(fp, "# HELP jemalloc_allocated_bytes Bytes allocated by jemalloc\n");
    fprintf(fp, "# TYPE jemalloc_allocated_bytes gauge\n");
    fprintf(fp, "jemalloc_allocated_bytes %zu\n", s.allocated);

    fprintf(fp, "# HELP jemalloc_active_bytes Active pages in jemalloc\n");
    fprintf(fp, "# TYPE jemalloc_active_bytes gauge\n");
    fprintf(fp, "jemalloc_active_bytes %zu\n", s.active);

    fprintf(fp, "# HELP jemalloc_metadata_bytes Metadata overhead\n");
    fprintf(fp, "# TYPE jemalloc_metadata_bytes gauge\n");
    fprintf(fp, "jemalloc_metadata_bytes %zu\n", s.metadata);

    fprintf(fp, "# HELP jemalloc_resident_bytes Resident set size\n");
    fprintf(fp, "# TYPE jemalloc_resident_bytes gauge\n");
    fprintf(fp, "jemalloc_resident_bytes %zu\n", s.resident);

    fprintf(fp, "# HELP jemalloc_mapped_bytes Mapped memory\n");
    fprintf(fp, "# TYPE jemalloc_mapped_bytes gauge\n");
    fprintf(fp, "jemalloc_mapped_bytes %zu\n", s.mapped);
}

{
  "dashboard": {
    "title": "jemalloc Memory Dashboard",
    "panels": [
      {
        "title": "Allocated Memory",
        "targets": [{"expr": "jemalloc_allocated_bytes"}]
      },
      {
        "title": "RSS (Resident)",
        "targets": [{"expr": "jemalloc_resident_bytes"}]
      },
      {
        "title": "Fragmentation Ratio",
        "targets": [{"expr": "jemalloc_active_bytes / jemalloc_allocated_bytes"}]
      }
    ]
  }
}

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
spec:
  replicas: 3
  template:
    spec:
      containers:
      - name: app
        image: my-app:latest
        env:
        - name: LD_PRELOAD
          value: "/usr/lib/x86_64-linux-gnu/libjemalloc.so.2"
        - name: MALLOC_CONF
          value: "narenas:4,dirty_decay_ms:2000,muzzy_decay_ms:5000,background_thread:true"
        resources:
          requests:
            memory: "512Mi"
            cpu: "500m"
          limits:
            memory: "1Gi"      # RSS 的 1.5-2 倍缓冲
            cpu: "2000m"

# 最佳实践：多阶段构建
FROM ubuntu:22.04 AS builder

# 安装构建依赖
RUN apt-get update && apt-get install -y \
    build-essential libjemalloc-dev \
    && rm -rf /var/lib/apt/lists/*

WORKDIR /build
COPY . .
RUN gcc -O2 -g -o my_server main.c -ljemalloc -lpthread

# 最小化运行镜像
FROM ubuntu:22.04

RUN apt-get update && apt-get install -y --no-install-recommends \
    libjemalloc2 \
    ca-certificates \
    && rm -rf /var/lib/apt/lists/*

# 创建非 root 用户
RUN useradd -r -s /bin/false appuser
USER appuser

COPY --from=builder /build/my_server /usr/local/bin/

ENV LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libjemalloc.so.2
ENV MALLOC_CONF="narenas:4,dirty_decay_ms:2000,background_thread:true"

EXPOSE 8080
HEALTHCHECK --interval=30s --timeout=3s \
  CMD curl -f http://localhost:8080/health || exit 1

CMD ["my_server"]

FROM alpine:3.18 AS builder

RUN apk add --no-cache build-base jemalloc-dev

WORKDIR /build
COPY . .
RUN gcc -O2 -g -o my_server main.c -ljemalloc -lpthread

FROM alpine:3.18

RUN apk add --no-cache jemalloc curl

COPY --from=builder /build/my_server /usr/local/bin/

ENV LD_PRELOAD=/usr/lib/libjemalloc.so.2
ENV MALLOC_CONF="narenas:2,dirty_decay_ms:1000,background_thread:true"

CMD ["my_server"]

# 检查库文件是否在容器内存在
docker run --rm my-app ls /usr/lib/x86_64-linux-gnu/libjemalloc*

# 检查架构匹配
docker run --rm my-app file /usr/lib/x86_64-linux-gnu/libjemalloc.so.2

# 检查是否被加载
docker run --rm my-app env | grep LD_PRELOAD
docker run --rm my-app cat /proc/1/maps | grep jemalloc

# 排查步骤
# 1. 检查 jemalloc 是否生效
docker exec <container> cat /proc/1/maps | grep jemalloc

# 2. 触发手动回收
docker exec <container> kill -USR1 1

# 3. 检查脏页配置
docker exec <container> env | grep MALLOC_CONF

# 4. 查看 jemalloc 统计
docker exec <container> sh -c \
  'MALLOC_CONF="stats_print:true" /usr/local/bin/my_server --once'

# 检查 OOM 事件
kubectl describe pod <pod-name> | grep -A5 "Last State"
dmesg | grep -i "out of memory"

# 解决方案：
# 1. 增加 memory limits
# 2. 减小 dirty_decay_ms
# 3. 减少 narenas
# 4. 检查是否有内存泄漏（使用 prof）

# Dockerfile.production
FROM ubuntu:22.04 AS jemalloc-build

RUN apt-get update && apt-get install -y \
    build-essential autoconf automake libtool wget \
    && rm -rf /var/lib/apt/lists/*

RUN wget -q https://github.com/jemalloc/jemalloc/releases/download/5.3.0/jemalloc-5.3.0.tar.bz2 \
    && tar xjf jemalloc-5.3.0.tar.bz2 \
    && cd jemalloc-5.3.0 \
    && ./configure \
        --prefix=/opt/jemalloc \
        --enable-prof \
        --enable-stats \
    && make -j$(nproc) && make install

FROM ubuntu:22.04 AS app-build

COPY --from=jemalloc-build /opt/jemalloc /opt/jemalloc
ENV PKG_CONFIG_PATH=/opt/jemalloc/lib/pkgconfig

RUN apt-get update && apt-get install -y build-essential pkg-config && rm -rf /var/lib/apt/lists/*
WORKDIR /build
COPY . .
RUN gcc -O2 -g -o my_server main.c \
    $(pkg-config --cflags --libs jemalloc) -lpthread

FROM ubuntu:22.04

COPY --from=jemalloc-build /opt/jemalloc /opt/jemalloc

RUN apt-get update && apt-get install -y --no-install-recommends \
    ca-certificates curl \
    && rm -rf /var/lib/apt/lists/* \
    && useradd -r -s /bin/false appuser

COPY --from=app-build /build/my_server /usr/local/bin/

USER appuser

ENV LD_PRELOAD=/opt/jemalloc/lib/libjemalloc.so.2
ENV LD_LIBRARY_PATH=/opt/jemalloc/lib
ENV MALLOC_CONF="narenas:4,dirty_decay_ms:2000,muzzy_decay_ms:5000,background_thread:true,prof:true,prof_active:true,prof_prefix:/tmp/jeprof"

EXPOSE 8080
CMD ["my_server"]