android.os
Class Process

java.lang.Object
  android.os.Process

public class Process
extends Object

Tools for managing OS processes.

Field Summary

static String	ANDROID_SHARED_MEDIA Name of a process for running the platform's media services.
static int	BLUETOOTH_GID Defines a secondary group id for access to the bluetooth hardware.
static int	FIRST_APPLICATION_UID Defines the start of a range of UIDs (and GIDs), going from this number to LAST_APPLICATION_UID that are reserved for assigning to applications.
static String	GOOGLE_SHARED_APP_CONTENT Name of the process that Google content providers can share.
static int	LAST_APPLICATION_UID Last of application-specific UIDs starting at FIRST_APPLICATION_UID.
static int	PHONE_UID Defines the UID/GID under which the telephony code runs.
static int	PROC_COMBINE
static int	PROC_OUT_FLOAT
static int	PROC_OUT_LONG
static int	PROC_OUT_STRING
static int	PROC_PARENS
static int	PROC_SPACE_TERM
static int	PROC_TERM_MASK
static int	PROC_ZERO_TERM
static int	SIGNAL_KILL
static int	SIGNAL_QUIT
static int	SIGNAL_USR1
(package private) static boolean	sPreviousZygoteOpenFailed true if previous zygote open failed
static int	SYSTEM_UID Defines the UID/GID under which system code runs.
(package private) static DataInputStream	sZygoteInputStream
(package private) static LocalSocket	sZygoteSocket
(package private) static BufferedWriter	sZygoteWriter
static int	THREAD_PRIORITY_AUDIO Standard priority of audio threads.
static int	THREAD_PRIORITY_BACKGROUND Standard priority background threads.
static int	THREAD_PRIORITY_DEFAULT Standard priority of application threads.
static int	THREAD_PRIORITY_DISPLAY Standard priority of system display threads, involved in updating the user interface.
static int	THREAD_PRIORITY_FOREGROUND Standard priority of threads that are currently running a user interface that the user is interacting with.
static int	THREAD_PRIORITY_LESS_FAVORABLE Minimum increment to make a priority less favorable.
static int	THREAD_PRIORITY_LOWEST Lowest available thread priority.
static int	THREAD_PRIORITY_MORE_FAVORABLE Minimum increment to make a priority more favorable.
static int	THREAD_PRIORITY_URGENT_AUDIO Standard priority of the most important audio threads.
static int	THREAD_PRIORITY_URGENT_DISPLAY Standard priority of the most important display threads, for compositing the screen and retrieving input events.
(package private) static int	ZYGOTE_RETRY_MILLIS retry interval for opening a zygote socket

Constructor Summary

Process()

Method Summary

static long	getElapsedCpuTime() Returns elapsed milliseconds of the time this process has run.
static int	getFreeMemory()
static int	getGidForName(String name) Returns the GID assigned to a particular user name, or -1 if there is none.
static int[]	getPids(String path, int[] lastArray)
static long	getPss(int pid) Gets the total Pss value for a given process, in bytes.
static int	getThreadPriority(int tid) Return the current priority of a thread, based on Linux priorities.
static int	getUidForName(String name) Returns the UID assigned to a partlicular user name, or -1 if there is none.
static void	killProcess(int pid) Kill the process with the given PID.
static int	myPid() Returns the identifier of this process, which can be used with killProcess(int) and sendSignal(int, int).
static int	myTid() Returns the identifier of the calling thread, which be used with setThreadPriority(int, int).
static boolean	readProcFile(String file, int[] format, String[] outStrings, long[] outLongs, float[] outFloats)
static void	readProcLines(String path, String[] reqFields, long[] outSizes)
static void	sendSignal(int pid, int signal) Send a signal to the given process.
static void	setArgV0(String text) Change this process's argv[0] parameter.
static int	setGid(int uid)
static boolean	setOomAdj(int pid, int amt) Set the out-of-memory badness adjustment for a process.
static void	setThreadPriority(int priority) Set the priority of the calling thread, based on Linux priorities.
static void	setThreadPriority(int tid, int priority) Set the priority of a thread, based on Linux priorities.
static int	setUid(int uid)
static int	start(String processClass, int uid, int gid, int[] gids, boolean enableDebugger, String[] zygoteArgs) Start a new process.
static int	start(String processClass, String niceName, int uid, int gid, int[] gids, boolean enableDebugger, String[] zygoteArgs) Start a new process.
static boolean	supportsProcesses() Determine whether the current environment supports multiple processes.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

ANDROID_SHARED_MEDIA

public static final String ANDROID_SHARED_MEDIA

Name of a process for running the platform's media services.

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Constant Field Values

GOOGLE_SHARED_APP_CONTENT

public static final String GOOGLE_SHARED_APP_CONTENT

Name of the process that Google content providers can share.

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Constant Field Values

SYSTEM_UID

public static final int SYSTEM_UID

Defines the UID/GID under which system code runs.

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Constant Field Values

PHONE_UID

public static final int PHONE_UID

Defines the UID/GID under which the telephony code runs.

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Constant Field Values

FIRST_APPLICATION_UID

public static final int FIRST_APPLICATION_UID

Defines the start of a range of UIDs (and GIDs), going from this number to LAST_APPLICATION_UID that are reserved for assigning to applications.

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Constant Field Values

LAST_APPLICATION_UID

public static final int LAST_APPLICATION_UID

Last of application-specific UIDs starting at FIRST_APPLICATION_UID.

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Constant Field Values

BLUETOOTH_GID

public static final int BLUETOOTH_GID

Defines a secondary group id for access to the bluetooth hardware.

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Constant Field Values

THREAD_PRIORITY_DEFAULT

public static final int THREAD_PRIORITY_DEFAULT

Standard priority of application threads. Use with setThreadPriority(int) and setThreadPriority(int, int), not with the normal Thread class.

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Constant Field Values

THREAD_PRIORITY_LOWEST

public static final int THREAD_PRIORITY_LOWEST

Lowest available thread priority. Only for those who really, really don't want to run if anything else is happening. Use with setThreadPriority(int) and setThreadPriority(int, int), not with the normal Thread class.

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Constant Field Values

THREAD_PRIORITY_BACKGROUND

public static final int THREAD_PRIORITY_BACKGROUND

Standard priority background threads. This gives your thread a slightly lower than normal priority, so that it will have less chance of impacting the responsiveness of the user interface. Use with setThreadPriority(int) and setThreadPriority(int, int), not with the normal Thread class.

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Constant Field Values

THREAD_PRIORITY_FOREGROUND

public static final int THREAD_PRIORITY_FOREGROUND

Standard priority of threads that are currently running a user interface that the user is interacting with. Applications can not normally change to this priority; the system will automatically adjust your application threads as the user moves through the UI. Use with setThreadPriority(int) and setThreadPriority(int, int), not with the normal Thread class.

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Constant Field Values

THREAD_PRIORITY_DISPLAY

public static final int THREAD_PRIORITY_DISPLAY

Standard priority of system display threads, involved in updating the user interface. Applications can not normally change to this priority. Use with setThreadPriority(int) and setThreadPriority(int, int), not with the normal Thread class.

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Constant Field Values

THREAD_PRIORITY_URGENT_DISPLAY

public static final int THREAD_PRIORITY_URGENT_DISPLAY

Standard priority of the most important display threads, for compositing the screen and retrieving input events. Applications can not normally change to this priority. Use with setThreadPriority(int) and setThreadPriority(int, int), not with the normal Thread class.

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Constant Field Values

THREAD_PRIORITY_AUDIO

public static final int THREAD_PRIORITY_AUDIO

Standard priority of audio threads. Applications can not normally change to this priority. Use with setThreadPriority(int) and setThreadPriority(int, int), not with the normal Thread class.

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Constant Field Values

THREAD_PRIORITY_URGENT_AUDIO

public static final int THREAD_PRIORITY_URGENT_AUDIO

Standard priority of the most important audio threads. Applications can not normally change to this priority. Use with setThreadPriority(int) and setThreadPriority(int, int), not with the normal Thread class.

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Constant Field Values

THREAD_PRIORITY_MORE_FAVORABLE

public static final int THREAD_PRIORITY_MORE_FAVORABLE

Minimum increment to make a priority more favorable.

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Constant Field Values

THREAD_PRIORITY_LESS_FAVORABLE

public static final int THREAD_PRIORITY_LESS_FAVORABLE

Minimum increment to make a priority less favorable.

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Constant Field Values

SIGNAL_QUIT

public static final int SIGNAL_QUIT

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Constant Field Values

SIGNAL_KILL

public static final int SIGNAL_KILL

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Constant Field Values

SIGNAL_USR1

public static final int SIGNAL_USR1

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Constant Field Values

sZygoteSocket

static LocalSocket sZygoteSocket

sZygoteInputStream

static DataInputStream sZygoteInputStream

sZygoteWriter

static BufferedWriter sZygoteWriter

sPreviousZygoteOpenFailed

static boolean sPreviousZygoteOpenFailed

true if previous zygote open failed

ZYGOTE_RETRY_MILLIS

static final int ZYGOTE_RETRY_MILLIS

retry interval for opening a zygote socket

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Constant Field Values

PROC_TERM_MASK

public static final int PROC_TERM_MASK

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Constant Field Values

PROC_ZERO_TERM

public static final int PROC_ZERO_TERM

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Constant Field Values

PROC_SPACE_TERM

public static final int PROC_SPACE_TERM

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Constant Field Values

PROC_COMBINE

public static final int PROC_COMBINE

See Also:

Constant Field Values

PROC_PARENS

public static final int PROC_PARENS

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Constant Field Values

PROC_OUT_STRING

public static final int PROC_OUT_STRING

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Constant Field Values

PROC_OUT_LONG

public static final int PROC_OUT_LONG

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Constant Field Values

PROC_OUT_FLOAT

public static final int PROC_OUT_FLOAT

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Constant Field Values

Constructor Detail

Process

public Process()

Method Detail

start

public static final int start(String processClass,
                              String niceName,
                              int uid,
                              int gid,
                              int[] gids,
                              boolean enableDebugger,
                              String[] zygoteArgs)

Start a new process.

If processes are enabled, a new process is created and the static main() function of a processClass is executed there. The process will continue running after this function returns.

If processes are not enabled, a new thread in the caller's process is created and main() of processClass called there.

The niceName parameter, if not an empty string, is a custom name to give to the process instead of using processClass. This allows you to make easily identifyable processes even if you are using the same base processClass to start them.

Parameters:

processClass - The class to use as the process's main entry point.

niceName - A more readable name to use for the process.

uid - The user-id under which the process will run.

gid - The group-id under which the process will run.

gids - Additional group-ids associated with the process.

enableDebugger - True if debugging should be enabled for this process.

zygoteArgs - Additional arguments to supply to the zygote process.

Returns:

int If > 0 the pid of the new process; if 0 the process is being emulated by a thread

Throws:

RuntimeException - on fatal start failure

start

public static final int start(String processClass,
                              int uid,
                              int gid,
                              int[] gids,
                              boolean enableDebugger,
                              String[] zygoteArgs)

Start a new process. Don't supply a custom nice name.

getElapsedCpuTime

public static final long getElapsedCpuTime()

Returns elapsed milliseconds of the time this process has run.

Returns:

Returns the number of milliseconds this process has return.

myPid

public static final int myPid()

Returns the identifier of this process, which can be used with killProcess(int) and sendSignal(int, int).

myTid

public static final int myTid()

Returns the identifier of the calling thread, which be used with setThreadPriority(int, int).

getUidForName

public static final int getUidForName(String name)

Returns the UID assigned to a partlicular user name, or -1 if there is none. If the given string consists of only numbers, it is converted directly to a uid.

getGidForName

public static final int getGidForName(String name)

Returns the GID assigned to a particular user name, or -1 if there is none. If the given string consists of only numbers, it is converted directly to a gid.

setThreadPriority

public static final void setThreadPriority(int tid,
                                           int priority)
                                    throws IllegalArgumentException,
                                           SecurityException

Set the priority of a thread, based on Linux priorities.

Parameters:

tid - The identifier of the thread/process to change.

priority - A Linux priority level, from -20 for highest scheduling priority to 19 for lowest scheduling priority.

Throws:

IllegalArgumentException - Throws IllegalArgumentException if tid does not exist.

SecurityException - Throws SecurityException if your process does not have permission to modify the given thread, or to use the given priority.

setThreadPriority

public static final void setThreadPriority(int priority)
                                    throws IllegalArgumentException,
                                           SecurityException

Set the priority of the calling thread, based on Linux priorities. See setThreadPriority(int, int) for more information.

Parameters:

priority - A Linux priority level, from -20 for highest scheduling priority to 19 for lowest scheduling priority.

Throws:

IllegalArgumentException - Throws IllegalArgumentException if tid does not exist.

SecurityException - Throws SecurityException if your process does not have permission to modify the given thread, or to use the given priority.

See Also:

setThreadPriority(int, int)

getThreadPriority

public static final int getThreadPriority(int tid)
                                   throws IllegalArgumentException

Return the current priority of a thread, based on Linux priorities.

Parameters:

tid - The identifier of the thread/process to change.

Returns:

Returns the current priority, as a Linux priority level, from -20 for highest scheduling priority to 19 for lowest scheduling priority.

Throws:

IllegalArgumentException - Throws IllegalArgumentException if tid does not exist.

supportsProcesses

public static final boolean supportsProcesses()

Determine whether the current environment supports multiple processes.

Returns:

Returns true if the system can run in multiple processes, else false if everything is running in a single process.

setOomAdj

public static final boolean setOomAdj(int pid,
                                      int amt)

Set the out-of-memory badness adjustment for a process.

Parameters:

pid - The process identifier to set.

amt - Adjustment value -- linux allows -16 to +15.

Returns:

Returns true if the underlying system supports this feature, else false.

setArgV0

public static final void setArgV0(String text)

Change this process's argv[0] parameter. This can be useful to show more descriptive information in things like the 'ps' command.

Parameters:

text - The new name of this process.

killProcess

public static final void killProcess(int pid)

Kill the process with the given PID. Note that, though this API allows us to request to kill any process based on its PID, the kernel will still impose standard restrictions on which PIDs you are actually able to kill. Typically this means only the process running the caller's packages/application and any additional processes created by that app; packages sharing a common UID will also be able to kill each other's processes.

setUid

public static final int setUid(int uid)

setGid

public static final int setGid(int uid)

sendSignal

public static final void sendSignal(int pid,
                                    int signal)

Send a signal to the given process.

Parameters:

pid - The pid of the target process.

signal - The signal to send.

getFreeMemory

public static final int getFreeMemory()

readProcLines

public static final void readProcLines(String path,
                                       String[] reqFields,
                                       long[] outSizes)

getPids

public static final int[] getPids(String path,
                                  int[] lastArray)

readProcFile

public static final boolean readProcFile(String file,
                                         int[] format,
                                         String[] outStrings,
                                         long[] outLongs,
                                         float[] outFloats)

getPss

public static final long getPss(int pid)

Gets the total Pss value for a given process, in bytes.

Parameters:

pid - the process to the Pss for

Returns:

the total Pss value for the given process in bytes, or -1 if the value cannot be determined