如何正确解释golang中的HeapInuse/HeapIdle/heapprereleased memory stats

我想监控我的golang程序的内存使用情况，并在系统缺少可用内存时清理一些内部缓存

问题是HeapAlloc/HeapInuse/heapprelessed统计数据并不总是正确相加（据我所知）

我正在查看可用系统内存（+buffers/cache）-

free

实用程序显示为

available

的值：

$ free
              total        used        free      shared  buff/cache   available
Mem:       16123232      409248    15113628         200      600356    15398424
Swap:      73242180       34560    73207620

我还看了一下HeapIdle-Heaprereleased，根据中的评论

现在的问题是：有时

Available+HeapInuse+HeapIdle-heapprerelease

超过了系统内存总量。通常在

HeapIdle

相当高且

heapredied

既不接近

HeapIdle

也不接近零时发生：

# Start of test
Available: 15379M, HeapAlloc: 49M, HeapInuse: 51M, HeapIdle: 58M, HeapReleased: 0M

# Work is in progress
# Looks good: 11795 + 3593 = 15388
Available: 11795M, HeapAlloc: 3591M, HeapInuse: 3593M, HeapIdle: 0M, HeapReleased: 0M

# Work has been done
# Looks good: 11745 + 45 + 3602 = 15392
Available: 11745M, HeapAlloc: 42M, HeapInuse: 45M, HeapIdle: 3602M, HeapReleased: 0M

# Golang released some memory to OS
# Looks good: 15224 + 14 + 3632 - 3552 = 15318
Available: 15224M, HeapAlloc: 10M, HeapInuse: 14M, HeapIdle: 3632M, HeapReleased: 3552M

# Some other work started
# Looks SUSPICIOUS: 13995 + 1285 + 2360 - 1769 = 15871
Available: 13995M, HeapAlloc: 1282M, HeapInuse: 1285M, HeapIdle: 2360M, HeapReleased: 1769M

# 5 seconds later
# Looks BAD: 13487 + 994 + 2652 - 398 = 16735 - more than system memory
Available: 13487M, HeapAlloc: 991M, HeapInuse: 994M, HeapIdle: 2652M, HeapReleased: 398M

# This bad situation holds for quite a while, even when work has been done
# Looks BAD: 13488 + 14 + 3631 - 489 = 16644
Available: 13488M, HeapAlloc: 10M, HeapInuse: 14M, HeapIdle: 3631M, HeapReleased: 489M

# It is strange that at this moment HeapIdle - HeapReleased = 3142
# > than 2134M of used memory reported by "free" utility.
$ free
              total        used        free      shared  buff/cache   available
Mem:       16123232     2185696    13337632         200      599904    13621988
Swap:      73242180       34560    73207620

# Still bad when another set of work started
# Looks BAD: 13066 + 2242 + 1403 = 16711
Available: 13066M, HeapAlloc: 2240M, HeapInuse: 2242M, HeapIdle: 1403M, HeapReleased: 0M

# But after 10 seconds it becomes good
# Looks good: 11815 + 2325 + 1320 = 15460
Available: 11815M, HeapAlloc: 2322M, HeapInuse: 2325M, HeapIdle: 1320M, HeapReleased: 0M

我不明白额外的1.3GB（16700-15400）内存是从哪里来的。在整个测试过程中，使用的交换空间保持不变。

交叉张贴在golang螺母上：

# Start of test
Available: 15379M, HeapAlloc: 49M, HeapInuse: 51M, HeapIdle: 58M, HeapReleased: 0M

# Work is in progress
# Looks good: 11795 + 3593 = 15388
Available: 11795M, HeapAlloc: 3591M, HeapInuse: 3593M, HeapIdle: 0M, HeapReleased: 0M

# Work has been done
# Looks good: 11745 + 45 + 3602 = 15392
Available: 11745M, HeapAlloc: 42M, HeapInuse: 45M, HeapIdle: 3602M, HeapReleased: 0M

# Golang released some memory to OS
# Looks good: 15224 + 14 + 3632 - 3552 = 15318
Available: 15224M, HeapAlloc: 10M, HeapInuse: 14M, HeapIdle: 3632M, HeapReleased: 3552M

# Some other work started
# Looks SUSPICIOUS: 13995 + 1285 + 2360 - 1769 = 15871
Available: 13995M, HeapAlloc: 1282M, HeapInuse: 1285M, HeapIdle: 2360M, HeapReleased: 1769M

# 5 seconds later
# Looks BAD: 13487 + 994 + 2652 - 398 = 16735 - more than system memory
Available: 13487M, HeapAlloc: 991M, HeapInuse: 994M, HeapIdle: 2652M, HeapReleased: 398M

# This bad situation holds for quite a while, even when work has been done
# Looks BAD: 13488 + 14 + 3631 - 489 = 16644
Available: 13488M, HeapAlloc: 10M, HeapInuse: 14M, HeapIdle: 3631M, HeapReleased: 489M

# It is strange that at this moment HeapIdle - HeapReleased = 3142
# > than 2134M of used memory reported by "free" utility.
$ free
              total        used        free      shared  buff/cache   available
Mem:       16123232     2185696    13337632         200      599904    13621988
Swap:      73242180       34560    73207620

# Still bad when another set of work started
# Looks BAD: 13066 + 2242 + 1403 = 16711
Available: 13066M, HeapAlloc: 2240M, HeapInuse: 2242M, HeapIdle: 1403M, HeapReleased: 0M

# But after 10 seconds it becomes good
# Looks good: 11815 + 2325 + 1320 = 15460
Available: 11815M, HeapAlloc: 2322M, HeapInuse: 2325M, HeapIdle: 1320M, HeapReleased: 0M