在这种情况下，我将指针从Go传递到C函数，C函数修改该指针值（填充数组），然后在Go代码上再次使用相同的指针，确保调用{{1 }}完成后将其释放。

我有时获得关于该指针的零引用，我很难理解原因。

在这里，Go中的对象是 cpuTimesC ，在C中是 cputicks 。

我也尝试过使函数返回指针，结果相同。最奇怪的是，如果我在函数的末尾添加一个printf语句，则需要花费更长的时间才能最终得到nil错误。

C.free

错误是：

package collector

/*
#cgo LDflaGS: -lperfstat
#include <stdlib.h>
#include <stdio.h>
#include <libperfstat.h>
#include <string.h>
#include <time.h>

u_longlong_t **ref;

int getcPUTicks(uint64_t **cputicks,size_t *cpu_ticks_len) {
    int i,ncpus,cputotal;
    perfstat_id_t firstcpu;
    perfstat_cpu_t *statp;

    cputotal = perfstat_cpu(NULL,NULL,sizeof(perfstat_cpu_t),0);
    if (cputotal <= 0){
        return -1;
   }

    statp = calloc(cputotal,sizeof(perfstat_cpu_t));
    if(statp==NULL){
            return -1;
    }
    ncpus = perfstat_cpu(&firstcpu,statp,cputotal);
    *cpu_ticks_len = ncpus*4;

    *cputicks = (uint64_t *) malloc(sizeof(uint64_t)*(*cpu_ticks_len));
    for (i = 0; i < ncpus; i++) {
        int offset = 4 * i;
        (*cputicks)[offset] = statp[i].user;
        (*cputicks)[offset+1] = statp[i].sys;
        (*cputicks)[offset+2] = statp[i].wait;
        (*cputicks)[offset+3] = statp[i].idle;
    }
    return 0;
}
*/
import "C"

import (
    "errors"
    "unsafe"
    "fmt"
    "github.com/prometheus/client_golang/prometheus"
)

const ClocksPerSec = float64(C.CLK_TCK)
const maxCPUTimesLen = 1024 * 4

type statCollector struct {
    cpu *prometheus.Desc
}

func init() {
    registerCollector("cpu",true,NewCPUCollector)
}

func NewCPUCollector() (Collector,error) {
    return &statCollector{
        cpu: nodeCPUSecondsDesc,},nil
}

func (c *statCollector) Update(ch chan<- prometheus.Metric) error {
    var fieldsCount = 4
    cpuFields := []string{"user","sys","wait","idle"}

    var (
        cpuTimesC       *C.uint64_t
        cpuTimesLength  C.size_t
    )

    if C.getcPUTicks(&cpuTimesC,&cpuTimesLength) == -1 {
        return errors.New("could not retrieve CPU times")
    }
    defer C.free(unsafe.Pointer(cpuTimesC))
    cput := (*[maxCPUTimesLen]C.u_longlong_t)(unsafe.Pointer(cpuTimesC))[:cpuTimesLength:cpuTimesLength]

    cpuTicks := make([]float64,cpuTimesLength)
    for i,value := range cput {
        cpuTicks[i] = float64(value) / ClocksPerSec
    }

    for i,value := range cpuTicks {
        cpux := fmt.Sprintf("CPU %d",i/fieldsCount)
        ch <- prometheus.MustNewConstMetric(c.cpu,prometheus.CounterValue,value,cpux,cpuFields[i%fieldsCount])
    }

    return nil
}

我知道它会在这里发生，因为出于某种原因 cpuTimesC 为零：

panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x33 addr=0x0 pc=0x1003fcec0]

goroutine 940 [running]:
github.com/dlopes7/aix-prometheus-exporter/collector.(*statCollector).Update(0xa000100000d21b8,0xa0001000028c480,0x0,0x0)
        /home/david/go/src/github.com/dlopes7/aix-prometheus-exporter/collector/cpu_aix.go:81 +0xf0
github.com/dlopes7/aix-prometheus-exporter/collector.execute(0x10043e7e7,0x3,0x1101120e0,0xa000100000d21b8,0xa0001000028c480)
        /home/david/go/src/github.com/dlopes7/aix-prometheus-exporter/collector/collector.go:95 +0x6c
github.com/dlopes7/aix-prometheus-exporter/collector.AIXCollector.Collect.func1(0xa0001000028c480,0xa000100000cd440,0x10043e7e7,0xa000100000d21b8)
        /home/david/go/src/github.com/dlopes7/aix-prometheus-exporter/collector/collector.go:115 +0x4c
created by github.com/dlopes7/aix-prometheus-exporter/collector.AIXCollector.Collect
        /home/david/go/src/github.com/dlopes7/aix-prometheus-exporter/collector/collector.go:114 +0xf8

为什么有时该对象为零，如何使它保留在内存中，直到我调用那个cput := (*[maxCPUTimesLen]C.u_longlong_t)(unsafe.Pointer(cpuTimesC))[:cpuTimesLength:cpuTimesLength] 为止？

如果有任何区别，此标记位于C.free的{​​{1}} AIX上。