Fix issue#1376, replace in with of for 'at that point of time'

Author: dongxuwang

glossary/index.md

@@ -372,7 +372,7 @@ A method’s _type signature_ comprises its name, the number, order, and types o
 The _uniform access principle_ states that variables and parameterless functions should be accessed using the same syntax. Scala supports this principle by not allowing parentheses to be placed at call sites of parameterless functions. As a result, a parameterless function definition can be changed to a `val`, or _vice versa_, without affecting client code.
 
 * #### unreachable
-At the Scala level, objects can become _unreachable_, at which point the memory they occupy may be reclaimed by the runtime. Unreachable does not necessarily mean unreferenced. Reference types (instances of `AnyRef`) are implemented as objects that reside on the JVM’s heap. When an instance of a reference type becomes unreachable, it indeed becomes unreferenced, and is available for garbage collection. Value types (instances of `AnyVal`) are implemented as both primitive type values and as instances of Java wrapper types (such as `java.lang.Integer`), which reside on the heap. Value type instances can be boxed (converted from a primitive value to a wrapper object) and unboxed (converted from a wrapper object to a primitive value) throughout the lifetime of the variables that refer to them. If a value type instance currently represented as a wrapper object on the JVM’s heap becomes unreachable, it indeed becomes unreferenced, and is available for garbage collection. But if a value type currently represented as a primitive value becomes unreachable, then it does not become unreferenced, because it does not exist as an object on the JVM’s heap at that point in time. The runtime may reclaim memory occupied by unreachable objects, but if an Int, for example, is implemented at run time by a primitive Java int that occupies some memory in the stack frame of an executing method, then the memory for that object is “reclaimed” when the stack frame is popped as the method completes. Memory for reference types, such as `Strings`, may be reclaimed by the JVM’s garbage collector after they become unreachable.
+At the Scala level, objects can become _unreachable_, at which point the memory they occupy may be reclaimed by the runtime. Unreachable does not necessarily mean unreferenced. Reference types (instances of `AnyRef`) are implemented as objects that reside on the JVM’s heap. When an instance of a reference type becomes unreachable, it indeed becomes unreferenced, and is available for garbage collection. Value types (instances of `AnyVal`) are implemented as both primitive type values and as instances of Java wrapper types (such as `java.lang.Integer`), which reside on the heap. Value type instances can be boxed (converted from a primitive value to a wrapper object) and unboxed (converted from a wrapper object to a primitive value) throughout the lifetime of the variables that refer to them. If a value type instance currently represented as a wrapper object on the JVM’s heap becomes unreachable, it indeed becomes unreferenced, and is available for garbage collection. But if a value type currently represented as a primitive value becomes unreachable, then it does not become unreferenced, because it does not exist as an object on the JVM’s heap at that point of time. The runtime may reclaim memory occupied by unreachable objects, but if an Int, for example, is implemented at run time by a primitive Java int that occupies some memory in the stack frame of an executing method, then the memory for that object is “reclaimed” when the stack frame is popped as the method completes. Memory for reference types, such as `Strings`, may be reclaimed by the JVM’s garbage collector after they become unreachable.
 
 * #### unreferenced
 See [unreachable](#unreachable).