{"id":55,"date":"2021-01-04T11:30:29","date_gmt":"2021-01-04T11:30:29","guid":{"rendered":"https:\/\/blog.gwlin.com\/?p=55"},"modified":"2023-03-29T18:17:23","modified_gmt":"2023-03-29T18:17:23","slug":"PHP \u5783\u573e\u56de\u6536\uff08GC\uff09\u673a\u5236","status":"publish","type":"post","link":"https:\/\/www.gwlin.com\/blog\/posts\/55","title":{"rendered":"PHP \u5783\u573e\u56de\u6536\uff08GC\uff09\u673a\u5236"},"content":{"rendered":"\n

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PHP\u7684\u5783\u573e\u56de\u6536\u673a\u5236\u7ecf\u7406\u8fc73\u4e2a\u4e0d\u540c\u7684\u65f6\u671f\uff1a5.2\u53ca\u4e4b\u524d\u7248\u672c\u30015.3-5.6\u30017.0\u4e4b\u540e\u3002\u4e0b\u9762\u5206\u522b\u8be6\u7ec6\u8bb2\u8bb2\u3002<\/p>\n\n\n\n

5.2\u53ca\u4e4b\u524d\u7248\u672c<\/strong><\/p>\n\n\n\n

\u9996\u5148\u6211\u4eec\u770b\u4e00\u4e0bPHP\u662f\u600e\u4e48\u50a8\u5b58\u53d8\u91cf\u7684\uff1a <\/p>\n\n\n\n

typedef struct _zval_struct {\n    zvalue_value value;\n    zend_uint refcount__gc;\n    zend_uchar type;\n    zend_uchar is_ref__gc;\n} zval;<\/code><\/pre>\n\n\n\n
\u4e0a\u9762\u662fPHP\u50a8\u5b58\u53d8\u91cf\u4fe1\u606f\u7684\u6e90\u7801\uff0c\u662f\u4e00\u4e2aC\u7684\u7ed3\u6784\u4f53\u3002\u6211\u4eec\u53ef\u4ee5\u770b\u5230\u6709\u4e24\u4e2a\u6709__gc\u540e\u7f00\u7684\u5b57\u6bb5\uff1arefcount__gc\uff0cis_ref__gc\u3002\u5176\u4e2drefcount\u662f\u5f15\u7528\u8ba1\u6570\uff0cis_ref\u662f\u201c\u662f\u5426\u662f\u5f15\u7528\u53d8\u91cf\u201d\u7684\u6807\u8bc6\u3002\u5f15\u7528\u8ba1\u6570\u4f1a\u5728\u6709\u53d8\u91cf\u6307\u5411\u5b83\u7684\u65f6\u5019\u52a01\uff0c\u53d8\u91cf\u88abunset\u7684\u65f6\u5019\u51cf1\u3002<\/p>\n\n\n\n
\u8fd9\u4e2a\u65f6\u671fPHP\u5e76\u6ca1\u6709\u4e13\u95e8\u7684\u5783\u573e\u56de\u6536\u5668 \uff0c\u8981\u5224\u65ad\u4e00\u4e2a\u53d8\u91cf\u5bb9\u5668\u7684\u662f\u5426\u53ef\u4ee5\u88ab\u91ca\u653e\uff0c\u5c31\u662f\u5224\u65adrefcount\u662f\u5426\u4e3a0\uff0c\u4e3a0\u7684\u65f6\u5019\u5c31\u7acb\u5373\u91ca\u653e\u3002<\/p>\n\n\n\n
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5.3-5.6\u7248\u672c<\/strong><\/p>\n\n\n\n
\u5728\u8fd9\u4e9b\u7248\u672c\u4e2d\uff0cPHP\u628a\u90a3\u4e9b\u53ef\u80fd\u662f\u5783\u573e\u7684\u53d8\u91cf\u5bb9\u5668\u653e\u5165\u6839\u7f13\u51b2\u533a\uff0c\u5f53\u6839\u7f13\u51b2\u533a\u6ee1\u4e86\u4e4b\u540e\u5c31\u4f1a\u542f\u52a8\u65b0\u7684\u5783\u573e\u56de\u6536\u673a\u5236\u3002<\/p>\n\n\n\n
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\u5728\u5783\u573e\u56de\u6536\u4e2d\uff0c\u5224\u65ad\u4e00\u4e2a\u5bb9\u5668\u662f\u5426\u662f\u771f\u7684\u5783\u573e\uff0c\u5176\u601d\u8def\u5e76\u4e0d\u590d\u6742\uff1a\u5982\u679c\u4e00\u4e2a\u53d8\u91cf\u5bb9\u5668\u7684refcount\u7684\u503c\u5168\u90e8\u6765\u81ea\u5176\u5f15\u7528\u81ea\u8eab\uff0c\u90a3\u4e48\u5b83\u662f\u4e00\u4e2a\u5783\u573e\u3002\u5177\u4f53\u64cd\u4f5c\u662f\u5bf9\u53d8\u91cf\u53ca\u5176\u6210\u5458\u7684refcount\u8fdb\u884c\u6a21\u62df\u5220\u9664\uff0c\u5373\u51cf1\u7684\u64cd\u4f5c\uff0c\u5982\u679c\u50cf\u6211\u4eec\u4e0a\u9762\u8bf4\u7684\uff0c\u5982\u679c\u5b83\u7684refcount\u503c\u90fd\u6765\u81ea\u5176\u6210\u5458\u5f15\u7528\u81ea\u8eab\uff0c\u90a3\u4e48\u6a21\u62df\u5220\u9664\u540e\uff0c\u5b83\u7684refcount\u503c\u5c31\u4f1a\u53d8\u62100\uff0c\u56e0\u6b64\u6211\u4eec\u53ef\u4ee5\u65ad\u5b9a\u5b83\u662f\u4e00\u4e2a\u5783\u573e\uff0c\u8981\u8fdb\u884c\u56de\u6536\u3002<\/p>\n\n\n\n
7.0\u4e4b\u540e<\/strong><\/p>\n\n\n\n
PHP7\u5bf9\u6bd4PHP5\u5728\u6027\u80fd\u4e0a\u662f\u4e00\u4e2a\u5f88\u5927\u7684\u63d0\u5347\uff0c\u5185\u5b58\u6d88\u8017\u4e5f\u8981\u5c11\u4e0d\u5c11\u3002\u8fd9\u662f\u5f97\u76ca\u4e8ePHP\u53d8\u91cf\u5bb9\u5668zval\u7684\u5168\u65b0\u8bbe\u8ba1\u3002<\/p>\n\n\n\n
struct _zval_struct {\n    zend_value value;\n    union {\n        struct {\n            ZEND_ENDIAN_LOHI_4(\n                zend_uchar type,\n                zend_uchar type_flags,\n                zend_uchar const_flags,\n                zend_uchar reserved)\n        } v;\n        uint32_t type_info;\n    } u1;\n    union {\n        uint32_t var_flags;\n        uint32_t next;                 \/\/ hash collision chain\n        uint32_t cache_slot;           \/\/ literal cache slot\n        uint32_t lineno;               \/\/ line number (for ast nodes)\n        uint32_t num_args;             \/\/ arguments number for EX(This)\n        uint32_t fe_pos;               \/\/ foreach position\n        uint32_t fe_iter_idx;          \/\/ foreach iterator index\n    } u2;\n};<\/code><\/pre>\n\n\n\n
\u5728PHP7\u4e2d\u4e0d\u540c\u7c7b\u578b\u7684\u53d8\u91cf\u50a8\u5b58\u53ca\u9500\u6bc1\u7684\u65b9\u5f0f\u5e76\u4e0d\u76f8\u540c\u3002<\/p>\n\n\n\n
\u5bf9\u4e8e\u7b80\u5355\u53d8\u91cf\uff0c\u5982\u6574\u6570\u3001\u6d6e\u70b9\u6570\u3001\u5e03\u5c14\u503c\u7b49\uff0cPHP\u4e0d\u518d\u662f\u5199\u65f6\u590d\u5236\uff0c\u800c\u662f\u5373\u65f6\u5206\u914d\uff0c\u56e0\u6b64\u4e0d\u9700\u8981refcount\u3002\u5f53unset\u6389\u4e00\u4e2a\u53d8\u91cf\u7684\u65f6\u5019\uff0c\u5bf9\u5e94\u7684zval\u5bb9\u5668\u4f1a\u88ab\u6807\u8bb0\u4e3aIS_UNDEF\uff0c\u7b49\u5f85\u91ca\u653e\u3002<\/p>\n\n\n\n
\u5bf9\u4e8e\u590d\u6742\u53d8\u91cf\u5982\u6570\u7ec4\u3001\u5bf9\u8c61\u7b49\uff0cPHP\u8fd8\u662f\u5171\u4eab\u4e00\u4e2azval\uff0c \u5199\u65f6\u590d\u5236\u3002\u5f53\u53d1\u751f\u53d8\u91cf\u5f15\u7528\u65f6\uff0cPHP\u4f1a\u5206\u914d\u4e00\u4e2azend_reference\u7ed3\u6784\u3002\u53d8\u91cf\u6307\u5411\u8fd9\u4e2azend_reference\u7ed3\u6784\uff0c\u91cc\u9762\u4fdd\u5b58\u7740refcount\u8ba1\u6570\uff0c\u8fd9\u4e2a\u7ed3\u6784\u518d\u6307\u5411\u5b9e\u9645zval\u5bb9\u5668\u3002\u56e0\u6b64\u5f53\u53d1\u751f\u5faa\u73af\u5f15\u7528\uff0c\u8fdb\u5165\u56de\u6536\u5468\u671f\u4e4b\u540e\uff0cPHP\u4f1a\u5bf9\u8fd9\u4e2azend_reference\u7ed3\u6784\u8fdb\u884c\u6a21\u62df\u5220\u9664\u64cd\u4f5c\uff0c\u5982\u540cPHP5\u4e00\u6837\u3002<\/p>\n\n\n\n
typedef struct _zend_refcounted_h {\n    uint32_t         refcount; \/\/ \u8bb0\u5f55 zend_value \u7684\u5f15\u7528\u6570\n    union {\n        struct {\n            zend_uchar    type,  \/\/ zend_value\u7684\u7c7b\u578b, \u4e0ezval.u1.type\u4e00\u81f4\n            zend_uchar    flags, \n            uint16_t      gc_info \/\/ GC\u4fe1\u606f\uff0c\u8bb0\u5f55\u5728 gc \u6c60\u4e2d\u7684\u4f4d\u7f6e\u548c\u989c\u8272\uff0c\u5783\u573e\u56de\u6536\u7684\u8fc7\u7a0b\u4f1a\u7528\u5230\n        } v;\n        uint32_t type_info;\n    } u;\n} zend_refcounted_h;<\/code><\/pre>\n\n\n\n
\u53c2\u8003\u6587\u7ae0\uff1a<\/p>\n\n\n\n
https:\/\/nikic.github.io\/2015\/05\/05\/Internal-value-representation-in-PHP-7-part-1.html<\/a><\/p>\n\n\n\n
https:\/\/learnku.com\/articles\/33451<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"
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