软引用 。当一个对象只具有软引用时，垃圾回收器只在内存不足的时候才回收它。
Soft Reference . When an object holds only soft references, GC collects it only if there is not enough memory.
有机固体废弃物如农业和林业生产废弃物、城市生活垃圾等具有一定的能量价值，应加以回收利用。
Organic wastes such as agricultural and forest residue, and municipal waste have certain energy values, which should be recovered and utilized.
其中的某个线程可能是负责执行垃圾回收的线程，因此这种死锁对整个进程具有重大影响。
One of those threads is likely to be a thread responsible for performing a garbage collection, so this deadlock can have a major impact on the entire process.
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