Django Performance 效能調校全方位指南 | Django 教學

pip install django-debug-toolbar

# settings.py（僅開發環境）

INSTALLED_APPS += ['debug_toolbar']

# 必須放在 Middleware 列表的最前面
MIDDLEWARE = [
    'debug_toolbar.middleware.DebugToolbarMiddleware',
] + MIDDLEWARE

# 只對本機 IP 顯示 Debug Toolbar
INTERNAL_IPS = ['127.0.0.1']

# urls.py
from django.conf import settings

if settings.DEBUG:
    import debug_toolbar
    urlpatterns = [
        path('__debug__/', include(debug_toolbar.urls)),
    ] + urlpatterns

class Article(models.Model):
    title = models.CharField(max_length=200)
    slug = models.SlugField(unique=True)   # unique=True 自動建立索引
    status = models.CharField(max_length=20, db_index=True)  # db_index 建立單欄索引
    created_at = models.DateTimeField(auto_now_add=True)

class Article(models.Model):
    title = models.CharField(max_length=200)
    author = models.ForeignKey(User, on_delete=models.CASCADE)
    status = models.CharField(max_length=20)
    created_at = models.DateTimeField(auto_now_add=True)

    class Meta:
        indexes = [
            # 複合索引：用於 filter(author=x, status=y) 查詢
            models.Index(
                fields=['author', 'status'],
                name='article_author_status_idx',
            ),
            # 降序索引：用於 order_by('-created_at') 查詢
            models.Index(
                fields=['-created_at'],
                name='article_created_desc_idx',
            ),
            # 條件索引（Django 4.0+，僅 PostgreSQL）
            models.Index(
                fields=['created_at'],
                name='article_published_idx',
                condition=models.Q(status='published'),
            ),
        ]

# 在 Django Shell 中查看 SQL 和 EXPLAIN
from django.db import connection

qs = Article.objects.filter(author_id=1, status='published')
print(qs.query)  # 查看生成的 SQL

with connection.cursor() as cursor:
    cursor.execute("EXPLAIN ANALYZE " + str(qs.query))
    for row in cursor.fetchall():
        print(row[0])
# Index Scan using article_author_status_idx → 索引生效
# Seq Scan on article → 全表掃描，需要建立索引！

# View 快取範例
from django.views.decorators.cache import cache_page

@cache_page(60 * 15)  # 快取 15 分鐘
def article_list(request):
    articles = Article.objects.filter(status='published')
    return render(request, 'articles/list.html', {'articles': articles})

# 低階快取 API 範例
from django.core.cache import cache

def get_popular_articles():
    cache_key = 'popular_articles'
    articles = cache.get(cache_key)
    if articles is None:
        articles = list(
            Article.objects.filter(status='published')
            .order_by('-view_count')[:10]
            .values('id', 'title', 'view_count')
        )
        cache.set(cache_key, articles, timeout=60 * 30)  # 快取 30 分鐘
    return articles

pip install whitenoise

# settings.py

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'whitenoise.middleware.WhiteNoiseMiddleware',  # 緊接在 SecurityMiddleware 之後
    # ... 其他 Middleware
]

# 開啟壓縮 + Manifest（檔名加 hash，支援長期快取）
STATICFILES_STORAGE = 'whitenoise.storage.CompressedManifestStaticFilesStorage'

# settings.py - 搭配 AWS S3 + CloudFront
STATIC_URL = 'https://d1234567.cloudfront.net/static/'

# 或使用 django-storages 自動上傳至 S3
STATICFILES_STORAGE = 'storages.backends.s3boto3.S3StaticStorage'
AWS_STORAGE_BUCKET_NAME = 'my-static-bucket'
AWS_S3_CUSTOM_DOMAIN = 'd1234567.cloudfront.net'

{% load cache %}

<!-- 快取側邊欄 300 秒，快取 key 為 "sidebar" -->
{% cache 300 sidebar %}
    <div class="sidebar">
        {% for category in categories %}
            <a href="{{ category.get_absolute_url }}">
                {{ category.name }} ({{ category.article_count }})
            </a>
        {% endfor %}
    </div>
{% endcache %}

<!-- 依據使用者 ID 產生不同的快取版本 -->
{% cache 600 user_dashboard request.user.id %}
    <div class="dashboard">
        <!-- 使用者專屬的儀表板內容 -->
    </div>
{% endcache %}

<!-- 不佳：expensive_method() 被呼叫多次 -->
{% if article.get_comment_count > 0 %}
    <p>{{ article.get_comment_count }} 則留言</p>
{% endif %}

<!-- 改善：只呼叫一次 -->
{% with comment_count=article.get_comment_count %}
    {% if comment_count > 0 %}
        <p>{{ comment_count }} 則留言</p>
    {% endif %}
{% endwith %}

# settings.py - 審視每個 Middleware 是否必要

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',          # 必要：安全
    'whitenoise.middleware.WhiteNoiseMiddleware',             # 必要：靜態檔案
    'django.contrib.sessions.middleware.SessionMiddleware',   # 必要：Session
    'django.middleware.common.CommonMiddleware',              # 必要：URL 正規化
    'django.middleware.csrf.CsrfViewMiddleware',              # 必要：CSRF 防護
    'django.contrib.auth.middleware.AuthenticationMiddleware', # 必要：認證
    'django.contrib.messages.middleware.MessageMiddleware',   # 必要：訊息框架
    'django.middleware.clickjacking.XFrameOptionsMiddleware', # 必要：Clickjacking 防護
    # 'django.middleware.locale.LocaleMiddleware',            # 未使用多語系可移除
    # 'debug_toolbar.middleware.DebugToolbarMiddleware',      # 僅開發環境
]

# 不佳：每次請求都查詢資料庫
class SlowMiddleware:
    def __init__(self, get_response):
        self.get_response = get_response

    def __call__(self, request):
        # 每次請求都執行 DB 查詢 — 效能殺手！
        request.site_config = SiteConfig.objects.first()
        return self.get_response(request)

# 改善：搭配快取
class CachedMiddleware:
    def __init__(self, get_response):
        self.get_response = get_response

    def __call__(self, request):
        from django.core.cache import cache
        config = cache.get('site_config')
        if config is None:
            config = SiteConfig.objects.first()
            cache.set('site_config', config, timeout=300)  # 快取 5 分鐘
        request.site_config = config
        return self.get_response(request)

# settings.py

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': 'mydb',
        'USER': 'myuser',
        'PASSWORD': 'mypassword',
        'HOST': 'localhost',
        'PORT': '5432',
        'CONN_MAX_AGE': 60,   # 連線保持 60 秒
        # CONN_MAX_AGE = 0    # 預設：每次請求後關閉
        # CONN_MAX_AGE = None # 永久保持（需注意資料庫連線上限）
    }
}

# 使用 django-db-connection-pool
# pip install django-db-connection-pool

DATABASES = {
    'default': {
        'ENGINE': 'dj_db_conn_pool.backends.postgresql',
        'NAME': 'mydb',
        'POOL_OPTIONS': {
            'POOL_SIZE': 10,       # 連線池基本大小
            'MAX_OVERFLOW': 10,    # 允許超出的連線數
            'RECYCLE': 24 * 60 * 60,  # 連線回收週期（1 天）
        }
    }
}

# settings.py

MIDDLEWARE = [
    'django.middleware.gzip.GZipMiddleware',  # 放在最前面
    'django.middleware.security.SecurityMiddleware',
    # ... 其他 Middleware
]

# nginx.conf
gzip on;
gzip_types text/plain text/css application/json application/javascript text/xml;
gzip_min_length 1000;    # 小於 1KB 的回應不壓縮
gzip_comp_level 6;       # 壓縮等級（1-9，6 是效能與壓縮率的平衡點）
gzip_vary on;            # 加入 Vary: Accept-Encoding 標頭