删除共享内存后key为0x00000000的问题

一开始是

------ Shared Memory Segments --------
key        shmid      owner      perms      bytes      nattch     status      
0x00000000 0          root       600        134217728  129        dest         
0x4405004b 32769      gyf        666        84032      1                       

ipcrm -M 0x4405004b 后变成

------ Shared Memory Segments --------
key        shmid      owner      perms      bytes      nattch     status      
0x00000000 0          root       600        134217728  129        dest         
0x00000000 32769      gyf        666        84032      1          dest 

原因，还有进程占用着该共享内存，必须关闭该进程才会彻底清除