//   have observed 12 micros on 64-bit linux systems to wake up a parked thread). So if the
  //   timeout is small we shouldn't park(). This needs to be traded off with the cpu overhead of
  //   spinning, so we use SPIN_THRESHOLD_NANOS which is what AbstractQueuedSynchronizer uses for
  //   similar purposes.
  // * We want to behave reasonably for timeouts of 0

Hơn nữa, tuỳ vào hệ điều hành của bạn (vd Linux, Windows, macOS), có thể đã có Python được cài đặt sẵn. Trong trường hợp ấy, một vài gói nhiều khả năng đã được cài đặt trước với các phiên bản **cần thiết cho hệ thống của bạn**. Nếu bạn cài đặt các gói trong môi trường Python toàn cục, bạn có thể sẽ **phá vỡ** một số chương trình đã được cài đặt sẵn cùng hệ thống.

     * stack so that it is returned by the next call to {@link Iterator#next()}. If the element is
     * not in {@link #nextElements}, this method throws an {@link UnknownElementException}.
     *
     * <p>This method is used when testing iterators without a known ordering. We poll the target
     * iterator's next element and pass it to the reference iterator through this method so it can

Aber in den meisten Fällen, wenn wir so etwas machen, wollen wir nur, dass das Modell einige der Daten **filtert/entfernt**, so wie in diesem Beispiel.

import sun.misc.Unsafe;

/**
 * A package-local class holding common representation and mechanics for classes supporting dynamic
 * striping on 64bit values. The class extends Number so that concrete subclasses must publicly do
 * so.
 */
@SuppressWarnings("SunApi") // b/345822163
@GwtIncompatible
abstract class Striped64 extends Number {
  /*
   * This class maintains a lazily-initialized table of atomically

#!/bin/sh

FESS_CLASSPATH=$FESS_HOME/lib/classes

# JAVA_OPTS is not a built-in JVM mechanism but some people think it is so we
# warn them that we are not observing the value of $JAVA_OPTS
if [ ! -z "$JAVA_OPTS" ]; then
  echo -n "warning: ignoring JAVA_OPTS=$JAVA_OPTS; "
  echo "pass JVM parameters via FESS_JAVA_OPTS"
fi

if [ "x$FESS_MIN_MEM" = "x" ]; then
    FESS_MIN_MEM=256m
fi
if [ "x$FESS_MAX_MEM" = "x" ]; then
    FESS_MAX_MEM=2g

 *
 * @param <B> The concrete type of this builder (the 'self-type'). All the Builder methods of this
 *     class (such as {@link #named(String)}) return this type, so that Builder methods of more
 *     derived classes can be chained onto them without casting.
 * @param <G> The type of the generator to be passed to testers in the generated test suite. An

  protected void setUp() throws Exception {
    // Load the "normal" copy of SettableFuture and related classes.
    SettableFuture<?> unused = SettableFuture.create();
    // Hack to load AbstractFuture et. al. in a new classloader so that it re-reads the cancellation
    // cause system property.  This allows us to run with both settings of the property in one jvm
    // without resorting to even crazier hacks to reset static final boolean fields.

  protected void setUp() throws Exception {
    // Load the "normal" copy of SettableFuture and related classes.
    SettableFuture<?> unused = SettableFuture.create();
    // Hack to load AbstractFuture et. al. in a new classloader so that it re-reads the cancellation
    // cause system property.  This allows us to run with both settings of the property in one jvm
    // without resorting to even crazier hacks to reset static final boolean fields.

 * RegularImmutableBiMap}, which don't have to recopy the entries created by their {@code Builder}
 * implementations.
 *
 * <p>This base implementation has no key or value pointers, so instances of ImmutableMapEntry (but
 * not its subclasses) can be reused when copied from one ImmutableMap to another.
 *
 * @author Louis Wasserman
 */
@GwtIncompatible // unnecessary