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Tool之MemScope

[0]=0; } break; case 1: if(allocated [1]=0; } break; case 2: if(allocated [2]=0; } break; case 3: if(allocated [3]=0; } break; case 4: if(allocated [4]=0; } break; case 5: if(allocated

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Java JFR 民间指南 - 事件详解 - jdk.ThreadAllocationStatistics

(from jdk.ThreadAllocationStatistics): 105179160 Thread 28 allocated(from JMX): 209780040; allocated( jdk.ThreadAllocationStatistics): 314573616 Thread 30 allocated(from JMX): 419431216; allocated(from = NULL, "invariant"); //读取每个线程的 cooked_allocated_bytes() allocated.append(jt->cooked_allocated_bytes inline jlong Thread::cooked_allocated_bytes() { //原子读取 _allocated_bytes jlong allocated_bytes = ; } } return allocated_bytes; } 那么哪里会修改 _allocated_bytes 这个变量呢?

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    Python 源码学习(3):list 类型

    new_allocated = 0; num_allocated_bytes = new_allocated * sizeof(PyObject *); items = (PyObject newsize 在区间 [allocated / 2, allocated] 内(小于当前容量 allocated 且大于等于当前容量的一半 allocated >> 1),则将数组容量缩小为 newsize 4 newsize 3 new_allocated 4 newsize 4 new_allocated 4 newsize 5 new_allocated 8 newsize 6 new_allocated 8 newsize 7 new_allocated 8 newsize 8 new_allocated 8 newsize 9 new_allocated 16 newsize 10 new_allocated 16 newsize 11 new_allocated 16 newsize 12 new_allocated 16 newsize 13 new_allocated 16 newsize 14 new_allocated

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    Python 源码阅读:list

    Py_ssize_t allocated; allocated列表分配的空间, ob_size为已使用的空间 allocated 总的申请到的内存数量 ob_size 实际使用内存数量 等式: 然后初始化数据 结论 Py_SIZE(op) = size; op->allocated = size; 第一次生成list, 其allocated = ob_size list_resize 同时注意 /2 <= newsize <= allocated // 直接修改ob_size if (allocated >= newsize && newsize >= (allocated >> 1)) Py_SIZE(self) = newsize; self->allocated = new_allocated; } 即 if allocated/2 <= newsize <= allocated allocated 不变 ob_size = newsize else allocated = newsize + ((newsize >> 3) + (newsize < 9

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    Python: 浅析列表的变长变短

    ; Py_ssize_t allocated = self->allocated; /* Bypass realloc() when a previous overallocation the list. */ if (allocated >= newsize && newsize >= (allocated >> 1)) { assert(self- = new_allocated; return 0; } 在上面的代码中,频繁看到两个名词:newsize 和 new_allocated, 这里需要解释下,newsize 并不是 增加/减少 3 : 6) + newsize (因为下面的 newsize > 0) 当原allocated >= newsize 并且 newsize >= 原allocated / 2 时,不改变 allocated 不申请内存直接返回 第 n 次 append 列表原长度 新增成员数 原 allocated newsize new_allocated 1 0 1 0 0 + 1 = 1 3 + 1 = 4 2 1

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    模拟linux内存管理代码 转

    *next;     }; /*进程分配内存块链表的首指针*/ struct allocated_block *allocated_block_head = NULL; void king(struct =NULL)  {p=h;  h=h->next;   free(p);  } } void freenode1(struct allocated_block *h) {  struct allocated_block *find_process(int p) {  struct allocated_block *h;  h=allocated_block_head; while(h! *ab;     int size;     int ret;     ab=(struct allocated_block *)malloc(sizeof(struct allocated_block }     pre = allocated_block_head;     ab = allocated_block_head->next;     while(ab!

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    Python中list的实现

    (ob_size)之间的关系,ob_size的大小和len(L)是一样的,而allocated的大小是在内存中已经申请空间大小。 3 : 6) = 3 new_allocated += newsize = 3 + 1 = 4 resize ob_item (list of pointers) to size new_allocated 调整后大小 (new_allocated) = 新元素数量 (newsize) + 预留空间 (new_allocated) 调整后的空间肯定能存储 newsize 个元素。 当 newsize >= allocated,自然按照这个新的长度 "扩容" 内存。 而如果 newsize < allocated,且利用率低于一半呢? allocated newsize new_size + new_allocated 10 4 4 + 3 20 9

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    Open vSwitch系列之数据结构解析深入分析ofpbuf

    表示内存已经使用的字节数 当size_ = allocated时候表示内存用完。 */ #endif uint32_t allocated; /* Number of bytes allocated. static void ofpbuf_init__(struct ofpbuf *b, size_t allocated, enum ofpbuf_source source) { b->allocated = allocated;//设置申请的内存大小 即内存块大小 b->source = source;//内存的类型,当前实例是malloc类型 b->frame = NULL; 和base_ 指针 b->allocated = new_allocated; ofpbuf_set_base(b, new_base); // 重新设置data_ 指针

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    内存分配统计视图 | 全方位认识 sys 系统库

    ) AS object_schema, sys.format_bytes(SUM(IF(ibp.compressed_size = 0, 16384, compressed_size))) AS allocated ', 1), '`', '')) AS object_schema, SUM(IF(ibp.compressed_size = 0, 16384, compressed_size)) AS allocated | current_avg_alloc | current_max_alloc | total_allocated | +-------------+--------------------+---- | current_avg_alloc | current_max_alloc | total_allocated | +-------------+--------------------+---- | current_avg_alloc | current_max_alloc | total_allocated | +-----------+--------------------------+

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    NDIS 6 Net Buffer Lists and Net Buffers

    As a part of the retreat operation a new MDL and new data buffer have been allocated and pre-pended to Once a context area is allocated by a driver it can obtain a pointer to its own context area by calling The miniport driver allocated its own context area (Driver #1 Context Area) and then indicated the NBL to the NDIS intermediate driver which in turn allocated its own context area (Driver#2 Context Area) The destination NB, MDL and data buffer can be allocated by NdisAllocateNetBufferMdlAndData().

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    内存分配统计视图 | 全方位认识 sys 系统库

    ) AS object_schema, sys.format_bytes(SUM(IF(ibp.compressed_size = 0, 16384, compressed_size))) AS allocated ', 1), '`', '')) AS object_schema, SUM(IF(ibp.compressed_size = 0, 16384, compressed_size)) AS allocated | current_avg_alloc | current_max_alloc | total_allocated | +-------------+--------------------+---- | current_avg_alloc | current_max_alloc | total_allocated | +-------------+--------------------+---- | current_avg_alloc | current_max_alloc | total_allocated | +-----------+--------------------------+

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    DAY6:阅读 CUDA C编程接口之CUDA C runtime

    the use of page-locked (also known as pinned) host memory (as opposed to regular pageable host memory allocated To make these advantages available to all devices, the block needs to be allocated by passing the flag Write-Combining Memory【写合并内存】 By default page-locked host memory is allocated as cacheable. It can optionally be allocated as write-combining instead by passing flag cudaHostAllocWriteCombined By default page-locked host memory is allocated as cacheable.

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    Cgroup测试&CFS计算方法

    is allocated [ 2560] bytes [1236] - memory is allocated [ 3072] bytes ... /a.out 重启程序,在没超过64K前加到组面 [1544] - memory is allocated [ 61440] bytes [1544] - memory is allocated [ 61952] bytes [1544] - memory is allocated [ 62464] bytes [1544] - memory is allocated [ 62976] is allocated [ 65536] bytes [1544] - memory is allocated [ 66048] bytes [1544] - memory is allocated is allocated [ 70144] bytes [1544] - memory is allocated [ 70656] bytes [1544] - memory is allocated

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    python 元组的实现和探析

    . */ PyObject **ob_item; /* ob_item contains space for 'allocated' elements. == NULL implies ob_size == allocated == 0 * list.sort() temporarily sets allocated to -1 to detect 为了优化存储结构,避免每次增加元素都要重新分配内存,列表预分配的空间allocated 往往会大于ob_size。 因此allocated 和ob_size 的关系是:allocated >= len(list) = ob_size >= 0。 如果当前列表分配的空间已满(即allocated == len(list)),则会向系统请求更大的内存空间,并把原来的元素全部拷贝过去。

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    Python列表对象实现原理

    咋一看PyListObject对象的定义非常简单,除了通用对象都有的引用计数(ob_refcnt)、类型信息(ob_type),以及变长对象的长度(ob_size)之外,剩下的只有ob_item,和allocated ,ob_item是真正存放列表元素容器的指针,专门有一块内存用来存储列表元素,这块内存的大小就是allocated所能容纳的空间。 alloocated是列表所能容纳的元素大小,而且满足条件: 0 len(list) == ob_size ob_item == NULL 时 ob_size == allocated == 0 列表对象的创建 初始化ob_item中的元素的值为Null 设置PyListObject的allocated和ob_size。 满足allocated >= newsize && newsize >= (allocated /2)时,简单改变list的元素长度,PyListObject对象不会重新分配内存空间,否则重新分配内存空间

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    python源码阅读笔记之GC(二)

    However, if the arena has * become wholly allocated, we need to remove its * * When this arena_object is associated with an allocated arena * with at least one * * Else this arena_object is associated with an allocated arena * all of whose pools ; #ifdef PYMALLOC_DEBUG ++ntimes_arena_allocated; if (narenas_currently_allocated > narenas_highwater ) narenas_highwater = narenas_currently_allocated; #endif arenaobj->freepools = NULL;

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    Java JFR 民间指南 - 事件详解 - jdk.ObjectAllocationSample

    = load_allocated_bytes(thread); assert(allocated_bytes > 0, "invariant"); // obj_alloc_size_bytes if (allocated_bytes - _last_allocated_bytes < tlab_size_bytes) { return; } assert(obj_alloc_size_bytes 减去当前线程的 allocated_bytes //由于不是每次线程发生 TLAB 外分配的时候上报都会被采集,所以需要记录上次被采集时候的线程分配的 allocated_bytes 大小,计算与当前的差值就是本次上报的事件中的线程距离上次上报分配的对象大小 const size_t weight = allocated_bytes - _last_allocated_bytes; assert(weight > 0, "invariant"); 这个 threadLocal 变量 _last_allocated_bytes = allocated_bytes; return true; } return false;

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    【DB笔试面试561】在Oracle中,如何预估即将创建索引的大小?

    SERVEROUTPUT ON SQL> DECLARE 2 L_INDEX_DDL VARCHAR2(1000); 3 L_USED_BYTES NUMBER; 4 L_ALLOCATED_BYTES )', 7 USED_BYTES => L_USED_BYTES, 8 ALLOC_BYTES => L_ALLOCATED_BYTES ); 9 DBMS_OUTPUT.PUT_LINE('USED= ' || L_USED_BYTES || 'BYTES' || 10 ' ALLOCATED = ' || L_ALLOCATED_BYTES || 'BYTES'); 11 END; 12 / USED= 383105BYTES ALLOCATED= 2097152BYTES 说明:USED_BYTES代表实际使用的字节数,而ALLOCATED代表申请的字节数。

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    性能测试案例:redis获取不到连接池,Timeout waiting for idle object

    实例状态是ALLOCATED ? ALLOCATED表示在使用中,压测结束后,虽然连接释放了,但是资源没归还 ? 下面可以看到,dataSource为空 ? datasource reset after the connection returned to pool, it might reset the datasource after it was allocated to another thread 三、总结 出现很多实例状态是ALLOCATED,dataSource为null的原因: 在多线程时,如果dataSource在连接释放后重置(根据代码逻辑可知:连接释放前 ,资源已经归还,但是未重置),可能在重置前,这个dataSource已经分配给另外一个线程了,此时重置,就把已经获取了这个dataSource的线程的dataSource重置了,这样就导致很多状态是ALLOCATED

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    使用 memory_limit 限制 PHP 进程的内存使用

    ", ini_get('memory_limit')); echo sprintf('
    Amount of memory allocated to PHP: %0.3fM. ', memory_get_usage() / $M); echo sprintf('
    Total memory allocated from system: %0.3fM. Amount of memory allocated to PHP: 0.344M. Amount of memory allocated to PHP: 2.348M. Total memory allocated from system: 4.004M. success $char_count 为 20 时,即初始化一个占用内存 20M 的字符串,输出结果为 Current Amount of memory allocated to PHP: 0.346M. 注意,HTTP 状态码为 500, 也就是说执行到字符串初始化的时候,PHP 进程被系统干掉了。

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