微服務架構中的兩款流量防衛兵

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Building（團隊建設），廣爲流傳的一句話：","attrs":{}},{"type":"text","marks":[{"type":"strong","attrs":{}}],"text":"打仗是最好的團建，沒有參加過雙十一的叫同事，參加過雙十一的叫戰友。","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"上一篇我通過三國故事講解了服務雪崩和熔斷的機制，而且自己造了一個輪子：","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"熔斷器","attrs":{}}],"attrs":{}},{"type":"text","text":"。而這一篇會講解被一線大廠使用的兩款流量防控組件：","attrs":{}},{"type":"codeinline","content":[{"type":"text","text":"Sentinel","attrs":{}}],"attrs":{}},{"type":"text","text":" 和 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false，前端頁面告訴用戶“服務器當前正忙，請稍後再試。”","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"bulletedlist","content":[{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"strong","attrs":{}}],"text":"什麼是限流？","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":"none"},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/7d/7d064f52a0157544b0547888b8eed5a4.png","alt":null,"title":null,"style":null,"href":null,"fromPaste":false,"pastePass":false}}]}]},{"type":"listitem","attrs":{"listStyle":"none"},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"對請求的流量進行控制， 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設計理念","attrs":{}}]},{"type":"bulletedlist","content":[{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"阻止服務的雪崩效應。","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"快速失敗和快速恢復。","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"優雅降級。","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"使用資源隔離技術，如 bulkhead（艙壁隔離技術）、swimlane（泳道技術）、circuit breaker（斷路技術）。","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"近實時的監控、報警及運維操作。","attrs":{}}]}]}],"attrs":{}},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"Hystrix 線程池隔離技術","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"使用線程池隔離，比如說有 3 個服務 A、B、C，每個服務的線程池分配 10，20，30個線程，當 A 服務線程池中的 10 個線程都拿出來使用後，如果調用服務 A 的請求量增加，還想再增加線程是不行的，因爲 A 服務分配的線程已經用完了，不會拿其他的服務的線程，這樣就不會影響其他服務了。Hystrix 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，適合大部分場景，但需要設置服務的超時時間。","attrs":{}}]}]},{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"strong","attrs":{}}],"text":"信號量隔離技術","attrs":{}},{"type":"text","text":" ，適合內部比較複雜的業務，不涉及網絡請求問題。","attrs":{}}]}]}],"attrs":{}},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"三、Sentinel","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"3.1、Sentinel 是什麼","attrs":{}}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"Sentinel：面向分佈式服務架構的流量控制組件，主要以流量爲切入點，從限流、流量整形、熔斷降級、系統負載保護、熱點防護等多個維度來幫助開發者保障微服務的穩定性。","attrs":{}}]},{"type":"heading","attrs":{"align":null,"level":3},"content":[{"type":"text","text":"3.2、Sentinel 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當系統長期處於低水位的情況下，當流量突然增加時，直接把系統拉昇到高水位可能瞬間把系統壓垮。通過\"冷啓動\"，讓通過的流量緩慢增加，在一定時間內逐漸增加到閾值上限，給冷系統一個預熱的時間，避免冷系統被壓垮。","attrs":{}}]}]}],"attrs":{}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/65/659166aae14a20bbd94418d4ee46b1b3.png","alt":null,"title":null,"style":[{"key":"width","value":"75%"},{"key":"bordertype","value":"none"}],"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"bulletedlist","content":[{"type":"listitem","attrs":{"listStyle":null},"content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"strong","attrs":{}}],"text":"勻速排隊：","attrs":{}},{"type":"text","text":" 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