Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
    at java.util.Hashtable.<init>(Hashtable.java:261)
    at java.util.Hashtable.<init>(Hashtable.java:283)
    at java.util.Properties.<init>(Properties.java:143)
    at java.util.Properties.<init>(Properties.java:135
 
)
    at com.itheima.netty_chat.demo.TestGC.main(TestGC.java:23)
Heap
 PSYoungGen      total 7168K, used 90K [0x00000000ff600000, 0x0000000100000000, 0x0000000100000000)
  eden space 4096K, 2% used [0x00000000ff600000,0x00000000ff616918,0x00000000ffa00000)
  from space 3072K, 0% used [0x00000000ffa00000,0x00000000ffa00000,0x00000000ffd00000)
  to   space 3072K, 0% used [0x00000000ffd00000,0x00000000ffd00000,0x0000000100000000)
 ParOldGen       total 20480K, used 512K [
 
0x00000000fe200000, 0x00000000ff600000, 0x00000000ff600000)
  object space 20480K, 2% used [0x00000000fe200000,0x00000000fe280000,0x00000000ff600000)
 PSPermGen       total 21504K, used 2644K [0x00000000f9000000, 0x00000000fa500000, 0x00000000fe200000)
  object space 21504K, 12% used [0x00000000f9000000,0x00000000f9295198,0x00000000fa500000)

分析：java.lang.OutOfMemoryError: Java heap space