Exception in thread "Client thread" java.lang.OutOfMemoryError: unable to create new native thread
        at java.lang.Thread.start0(Native Method)
        at java.lang.Thread.start(Unknown Source)
        at java.util.concurrent.CompletableFuture$ThreadPerTaskExecutor.execute(Unknown Source)
        at java.util.concurrent.CompletableFuture.asyncRunStage(Unknown Source)
        at java.util.concurrent.CompletableFuture.runAsync(Unknown Source)
        at com.mojang.datafixers.DataFixerBuilder.build(DataFixerBuilder.java:70)
        at yu.b(SourceFile:151)
        at yu.<clinit>(SourceFile:146)
        at agj$a.a(SourceFile:461)
        at agj.a(SourceFile:135)
        at agj.<clinit>(SourceFile:138)
        at fk.t(SourceFile:69)
        at fk.a(SourceFile:92)
        at java.util.LinkedHashMap$LinkedEntrySet.forEach(Unknown Source)
        at fk.<clinit>(SourceFile:91)
        at qb.b(SourceFile:476)
        at cnd.<init>(SourceFile:364)
        at net.minecraft.client.main.Main.main(SourceFile:154)

内存不足，在hmcl的设置中调大

另外，记得使用最新版

http://www.mcbbs.net/thread-142335-1-1.html

Exception in thread "Client thread" java.lang.OutOfMemoryError: unable to create new native thread         at java.lang.Thread.start0(Native Method)         at java.lang.Thread.start(Unknown Source)         at java.util.concurrent.CompletableFuture$ThreadPerTaskExecutor.execute(Unknown Source)         at java.util.concurrent.CompletableFuture.asyncRunStage(Unknown Source)         at java.util.concurrent.CompletableFuture.runAsync(Unknown Source)         at com.mojang.datafixers.DataFixerBuilder.build(DataFixerBuilder.java:70)         at yu.b(SourceFile:151)         at yu.<clinit>(SourceFile:146)         at agj$a.a(SourceFile:461)         at agj.a(SourceFile:135)         at agj.<clinit>(SourceFile:138)         at fk.t(SourceFile:69)         at fk.a(SourceFile:92)         at java.util.LinkedHashMap$LinkedEntrySet.forEach(Unknown Source)         at fk.<clinit>(SourceFile:91)         at qb.b(SourceFile:476)         at cnd.<init>(SourceFile:364)         at net.minecraft.client.main.Main.main(SourceFile:154)

如果电脑内存不够分配1024mb可以加内存条，不行就换电脑

HMCL换一个2.7的或者3.1的实在不行把运行内存调低点