Java Clojure:输入流比读取器慢

我试图从输入流中读取字节，这比使用reader读取字符慢得多。我不明白为什么会这样。看看测试：

(defn r1
  [input]
  (loop []
    (when-not (= -1 (.read ^java.io.InputStream input))
      (recur))))

(defn r2
  [input]
  (loop []
    (when-not (.read input)
      (recur))))

(dotimes [_ 10] 
   (time (with-open [is (clojure.java.io/input-stream "15mb.log")]
     (r1 is))))

"Elapsed time: 111.608991 msecs"
"Elapsed time: 95.45663 msecs"
"Elapsed time: 148.789867 msecs"
"Elapsed time: 97.580527 msecs"
"Elapsed time: 113.093759 msecs"
"Elapsed time: 108.306019 msecs"
"Elapsed time: 107.71069 msecs"
"Elapsed time: 104.833343 msecs"
"Elapsed time: 174.701027 msecs"
"Elapsed time: 141.969629 msecs"

(dotimes [_ 10]
   (time (with-open [r (clojure.java.io/reader "15mb.log")]
      (r2 r))))

"Elapsed time: 0.635769 msecs"
"Elapsed time: 0.422315 msecs"
"Elapsed time: 0.355953 msecs"
"Elapsed time: 0.336128 msecs"
"Elapsed time: 0.333523 msecs"
"Elapsed time: 0.339613 msecs"
"Elapsed time: 0.329693 msecs"
"Elapsed time: 0.234213 msecs"
"Elapsed time: 0.209742 msecs"
"Elapsed time: 0.199334 msecs"

---

据我所知，clojure.java.io/input-stream使用BufferedInputStream，clojure.java.io/reader使用BufferedReader，因此没有理由在速度上有如此显著的差异。我错过什么了吗？

你的测试有缺陷。BufferedReader和BufferedInputStream在流的末尾都返回-1。因此，r2的测试也应该在not=-1时进行

虽然下面的测试方法不能精确到很小的毫秒级，但对于这个测试来说已经足够精确了，使用clojure的非常好的Criteriam基准库进行的测试也会产生类似的结果。再次更紧凑地发布测试，以便于复制/粘贴：

(let [testfile "zerofile"]    ; $ dd if=/dev/zero of=zerofile bs=1k count=1k
  (map (fn [func label]
         (println label)
         (dotimes [_ 3]
           (time (with-open [data (func testfile)]
                   (while (not= -1 (.read data)))))))
    [clojure.java.io/input-stream,  clojure.java.io/reader]
    ["Input Stream:" "\nReader:"]))

一个结果是：

Input Stream:
"Elapsed time: 624.01494 msecs"
"Elapsed time: 650.407183 msecs"
"Elapsed time: 627.244097 msecs"

Reader:
"Elapsed time: 706.776733 msecs"
"Elapsed time: 691.887275 msecs"
"Elapsed time: 703.918226 msecs"

---

你确定你的r2是正确的吗？你没有在那里使用readLine吗？如果测试结果是错误的，而不是将其与-1进行比较，则表明是，r2不正确。谢谢。谢谢你的帮助，我现在明白了。我的例子中有一个读者，我太快退出了。