Composer 之所以在安裝或更新依賴時(shí)感覺很慢，主要是因?yàn)橐蕾嚱馕?、元?shù)據(jù)獲取、自動加載優(yōu)化及環(huán)境配置等多方面因素疊加導(dǎo)致。1. 依賴解析采用回溯算法，需嘗試多種版本組合，項(xiàng)目越大、約束越多越耗時(shí)，可通過精簡 composer.json、使用具體版本約束來緩解；2. 默認(rèn)從 Packagist 獲取元數(shù)據(jù)可能受網(wǎng)絡(luò)影響，可使用鏡像或 DNS 加速；3. 自動加載生成和腳本執(zhí)行也會增加開銷，建議按需禁用 autoload 和 scripts；4. 使用舊版 Composer 或不當(dāng)?shù)?PHP 設(shè)置（如內(nèi)存限制、OPcache 未啟用）也會影響速度，應(yīng)升級 Composer 并優(yōu)化 PHP 配置。

Composer can sometimes feel painfully slow when installing or updating dependencies, especially if you're used to faster tools. The main reason usually boils down to how Composer resolves dependencies and handles package metadata.

1. Dependency Resolution Takes Time

Composer uses a backtracking algorithm to resolve dependencies, which means it tries different combinations of package versions until it finds one that works for all requirements. This process gets more complex as the number of packages and their version constraints increases.

• Large projects with many dependencies (like Laravel apps) are especially prone to this.
• Conflicting version constraints between packages make it even worse — Composer might try dozens of combinations before finding a valid solution.

What you can do:

• Keep your composer.json clean. Only include what you really need.
• Use specific version constraints instead of overly broad ones like dev-master or *, which force Composer to check more possibilities.
• Consider using --prefer-stable and --prefer-lowest only when necessary, as they add extra complexity during resolution.

2. Fetching Metadata from Packagist is Slow

By default, Composer fetches package metadata from Packagist, which can be slow depending on your location or network conditions. Even small delays per request can add up quickly, especially when dealing with hundreds of packages.

What you can do:

• Use a mirror or caching proxy like Satis for internal packages.
• Try switching to a faster DNS provider like Cloudflare (1.1.1.1) or Google (8.8.8.8).
• If you're in China, consider using a local Packagist mirror like http://ipnx.cn/link/1569ae888190eb8c53b218b0d529e1e9 via composer config repositories.packagist.org composer http://ipnx.cn/link/1569ae888190eb8c53b218b0d529e1e9.

3. Autoload Optimization and Scripts Add Overhead

After installing or updating packages, Composer regenerates the autoloader, which can take extra time — especially if you have lots of classes or use classmap. Plus, any custom scripts defined in scripts (e.g., clearing cache, generating files) will also run by default unless you disable them.

What you can do:

• Use composer install --no-autoloader or --no-scripts when speed matters more than full setup.
• Optimize your autoload with composer dump-autoload --optimize only when preparing for production.
• Avoid heavy logic in Composer scripts — keep them minimal and fast.

4. Outdated Composer Version or PHP Settings

Older versions of Composer may not be optimized for performance the way newer ones are. Also, certain PHP settings (like low memory limits or disabled opcache) can significantly impact Composer’s speed.

What you can do:

• Make sure you're running the latest stable version of Composer (composer self-update).
• Increase PHP memory limit (memory_limit) in your php.ini if Composer runs out of memory and slows down or fails.
• Enable OPcache in development environments — it helps Composer run faster, even if you’re not using it in production.

基本上就這些。
Composer 的速度問題通常不是單一原因造成的，而是多個(gè)因素疊加的結(jié)果。優(yōu)化時(shí)可以從依賴管理、網(wǎng)絡(luò)訪問、腳本執(zhí)行和環(huán)境配置幾個(gè)方面入手。多數(shù)情況下，哪怕只是調(diào)整一兩個(gè)設(shè)置，也能帶來明顯的提速效果。

以上是為什么作曲家花了這么長時(shí)間才能安裝或更新依賴關(guān)系？的詳細(xì)內(nèi)容。更多信息請關(guān)注PHP中文網(wǎng)其他相關(guān)文章！