Sur la base des réponses précédentes et de mon expérience personnelle, voici le code que j'utilise pour surveiller l'utilisation du CPU. Le code de cette classe est écrit en Java pur.
import java.io.IOException;
import java.io.RandomAccessFile;
/**
* Utilities available only on Linux Operating System.
*
* <p>
* A typical use is to assign a thread to CPU monitoring:
* </p>
*
* <pre>
* @Override
* public void run() {
* while (CpuUtil.monitorCpu) {
*
* LinuxUtils linuxUtils = new LinuxUtils();
*
* int pid = android.os.Process.myPid();
* String cpuStat1 = linuxUtils.readSystemStat();
* String pidStat1 = linuxUtils.readProcessStat(pid);
*
* try {
* Thread.sleep(CPU_WINDOW);
* } catch (Exception e) {
* }
*
* String cpuStat2 = linuxUtils.readSystemStat();
* String pidStat2 = linuxUtils.readProcessStat(pid);
*
* float cpu = linuxUtils.getSystemCpuUsage(cpuStat1, cpuStat2);
* if (cpu >= 0.0f) {
* _printLine(mOutput, "total", Float.toString(cpu));
* }
*
* String[] toks = cpuStat1.split(" ");
* long cpu1 = linuxUtils.getSystemUptime(toks);
*
* toks = cpuStat2.split(" ");
* long cpu2 = linuxUtils.getSystemUptime(toks);
*
* cpu = linuxUtils.getProcessCpuUsage(pidStat1, pidStat2, cpu2 - cpu1);
* if (cpu >= 0.0f) {
* _printLine(mOutput, "" + pid, Float.toString(cpu));
* }
*
* try {
* synchronized (this) {
* wait(CPU_REFRESH_RATE);
* }
* } catch (InterruptedException e) {
* e.printStackTrace();
* return;
* }
* }
*
* Log.i("THREAD CPU", "Finishing");
* }
* </pre>
*/
public final class LinuxUtils {
/** Return the first line of /proc/stat or null if failed. */
public String readSystemStat() {
RandomAccessFile reader = null;
String load = null;
try {
reader = new RandomAccessFile("/proc/stat", "r");
load = reader.readLine();
} catch (IOException ex) {
ex.printStackTrace();
} finally {
Streams.close(reader);
}
return load;
}
/**
* Compute and return the total CPU usage, in percent.
*
* @param start
* first content of /proc/stat. Not null.
* @param end
* second content of /proc/stat. Not null.
* @return the CPU use in percent, or -1f if the stats are inverted or on
* error
* @see {@link #readSystemStat()}
*/
public float getSystemCpuUsage(String start, String end) {
String[] stat = start.split(" ");
long idle1 = getSystemIdleTime(stat);
long up1 = getSystemUptime(stat);
stat = end.split(" ");
long idle2 = getSystemIdleTime(stat);
long up2 = getSystemUptime(stat);
// don't know how it is possible but we should care about zero and
// negative values.
float cpu = -1f;
if (idle1 >= 0 && up1 >= 0 && idle2 >= 0 && up2 >= 0) {
if ((up2 + idle2) > (up1 + idle1) && up2 >= up1) {
cpu = (up2 - up1) / (float) ((up2 + idle2) - (up1 + idle1));
cpu *= 100.0f;
}
}
return cpu;
}
/**
* Return the sum of uptimes read from /proc/stat.
*
* @param stat
* see {@link #readSystemStat()}
*/
public long getSystemUptime(String[] stat) {
/*
* (from man/5/proc) /proc/stat kernel/system statistics. Varies with
* architecture. Common entries include: cpu 3357 0 4313 1362393
*
* The amount of time, measured in units of USER_HZ (1/100ths of a
* second on most architectures, use sysconf(_SC_CLK_TCK) to obtain the
* right value), that the system spent in user mode, user mode with low
* priority (nice), system mode, and the idle task, respectively. The
* last value should be USER_HZ times the second entry in the uptime
* pseudo-file.
*
* In Linux 2.6 this line includes three additional columns: iowait -
* time waiting for I/O to complete (since 2.5.41); irq - time servicing
* interrupts (since 2.6.0-test4); softirq - time servicing softirqs
* (since 2.6.0-test4).
*
* Since Linux 2.6.11, there is an eighth column, steal - stolen time,
* which is the time spent in other operating systems when running in a
* virtualized environment
*
* Since Linux 2.6.24, there is a ninth column, guest, which is the time
* spent running a virtual CPU for guest operating systems under the
* control of the Linux kernel.
*/
// with the following algorithm, we should cope with all versions and
// probably new ones.
long l = 0L;
for (int i = 2; i < stat.length; i++) {
if (i != 5) { // bypass any idle mode. There is currently only one.
try {
l += Long.parseLong(stat[i]);
} catch (NumberFormatException ex) {
ex.printStackTrace();
return -1L;
}
}
}
return l;
}
/**
* Return the sum of idle times read from /proc/stat.
*
* @param stat
* see {@link #readSystemStat()}
*/
public long getSystemIdleTime(String[] stat) {
try {
return Long.parseLong(stat[5]);
} catch (NumberFormatException ex) {
ex.printStackTrace();
}
return -1L;
}
/** Return the first line of /proc/pid/stat or null if failed. */
public String readProcessStat(int pid) {
RandomAccessFile reader = null;
String line = null;
try {
reader = new RandomAccessFile("/proc/" + pid + "/stat", "r");
line = reader.readLine();
} catch (IOException ex) {
ex.printStackTrace();
} finally {
Streams.close(reader);
}
return line;
}
/**
* Compute and return the CPU usage for a process, in percent.
*
* <p>
* The parameters {@code totalCpuTime} is to be the one for the same period
* of time delimited by {@code statStart} and {@code statEnd}.
* </p>
*
* @param start
* first content of /proc/pid/stat. Not null.
* @param end
* second content of /proc/pid/stat. Not null.
* @return the CPU use in percent or -1f if the stats are inverted or on
* error
* @param uptime
* sum of user and kernel times for the entire system for the
* same period of time.
* @return 12.7 for a cpu usage of 12.7% or -1 if the value is not available
* or an error occurred.
* @see {@link #readProcessStat(int)}
*/
public float getProcessCpuUsage(String start, String end, long uptime) {
String[] stat = start.split(" ");
long up1 = getProcessUptime(stat);
stat = end.split(" ");
long up2 = getProcessUptime(stat);
float ret = -1f;
if (up1 >= 0 && up2 >= up1 && uptime > 0.) {
ret = 100.f * (up2 - up1) / (float) uptime;
}
return ret;
}
/**
* Decode the fields of the file {@code /proc/pid/stat} and return (utime +
* stime)
*
* @param stat
* obtained with {@link #readProcessStat(int)}
*/
public long getProcessUptime(String[] stat) {
return Long.parseLong(stat[14]) + Long.parseLong(stat[15]);
}
/**
* Decode the fields of the file {@code /proc/pid/stat} and return (cutime +
* cstime)
*
* @param stat
* obtained with {@link #readProcessStat(int)}
*/
public long getProcessIdleTime(String[] stat) {
return Long.parseLong(stat[16]) + Long.parseLong(stat[17]);
}
/**
* Return the total CPU usage, in percent.
* <p>
* The call is blocking for the time specified by elapse.
* </p>
*
* @param elapse
* the time in milliseconds between reads.
* @return 12.7 for a CPU usage of 12.7% or -1 if the value is not
* available.
*/
public float syncGetSystemCpuUsage(long elapse) {
String stat1 = readSystemStat();
if (stat1 == null) {
return -1.f;
}
try {
Thread.sleep(elapse);
} catch (Exception e) {
}
String stat2 = readSystemStat();
if (stat2 == null) {
return -1.f;
}
return getSystemCpuUsage(stat1, stat2);
}
/**
* Return the CPU usage of a process, in percent.
* <p>
* The call is blocking for the time specified by elapse.
* </p>
*
* @param pid
* @param elapse
* the time in milliseconds between reads.
* @return 6.32 for a CPU usage of 6.32% or -1 if the value is not
* available.
*/
public float syncGetProcessCpuUsage(int pid, long elapse) {
String pidStat1 = readProcessStat(pid);
String totalStat1 = readSystemStat();
if (pidStat1 == null || totalStat1 == null) {
return -1.f;
}
try {
Thread.sleep(elapse);
} catch (Exception e) {
e.printStackTrace();
return -1.f;
}
String pidStat2 = readProcessStat(pid);
String totalStat2 = readSystemStat();
if (pidStat2 == null || totalStat2 == null) {
return -1.f;
}
String[] toks = totalStat1.split(" ");
long cpu1 = getSystemUptime(toks);
toks = totalStat2.split(" ");
long cpu2 = getSystemUptime(toks);
return getProcessCpuUsage(pidStat1, pidStat2, cpu2 - cpu1);
}
}
Il existe plusieurs façons d'exploiter cette classe. Vous pouvez appeler soit syncGetSystemCpuUsage o syncGetProcessCpuUsage mais chacun bloque le fil d'appel. Puisqu'un problème commun est de surveiller l'utilisation totale du CPU et l'utilisation du CPU du processus actuel en même temps, j'ai conçu une classe calculant les deux. Cette classe contient un thread dédié. La gestion de la sortie est spécifique à l'implémentation et vous devez coder la vôtre.
La classe peut être personnalisée par quelques moyens. La constante CPU_WINDOW définit la profondeur d'une lecture, c'est-à-dire le nombre de millisecondes entre les lectures et le calcul de la charge CPU correspondante. CPU_REFRESH_RATE est le temps entre chaque mesure de la charge du CPU. Ne définissez pas CPU_REFRESH_RATE à 0 car cela suspend le fil après la première lecture.
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.OutputStream;
import android.app.Application;
import android.os.Handler;
import android.os.HandlerThread;
import android.util.Log;
import my.app.LinuxUtils;
import my.app.Streams;
import my.app.TestReport;
import my.app.Utils;
public final class CpuUtil {
private static final int CPU_WINDOW = 1000;
private static final int CPU_REFRESH_RATE = 100; // Warning: anything but 0
private static HandlerThread mHandlerThread;
private static TestReport mOutput;
static {
mOutput = new TestReport();
mOutput.setDateFormat(Utils.getDateFormat(Utils.DATE_FORMAT_ENGLISH));
}
private static boolean monitorCpu;
/**
* Construct the class singleton. This method should be called in
* {@link Application#onCreate()}
*
* @param dir
* the parent directory
* @param append
* mode
*/
public static void setOutput(File dir, boolean append) {
try {
File file = new File(dir, "cpu.txt");
mOutput.setOutputStream(new FileOutputStream(file, append));
if (!append) {
mOutput.println(file.getAbsolutePath());
mOutput.newLine(1);
// print header
_printLine(mOutput, "Process", "CPU%");
mOutput.flush();
}
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
/** Start CPU monitoring */
public static boolean startCpuMonitoring() {
CpuUtil.monitorCpu = true;
mHandlerThread = new HandlerThread("CPU monitoring"); //$NON-NLS-1$
mHandlerThread.start();
Handler handler = new Handler(mHandlerThread.getLooper());
handler.post(new Runnable() {
@Override
public void run() {
while (CpuUtil.monitorCpu) {
LinuxUtils linuxUtils = new LinuxUtils();
int pid = android.os.Process.myPid();
String cpuStat1 = linuxUtils.readSystemStat();
String pidStat1 = linuxUtils.readProcessStat(pid);
try {
Thread.sleep(CPU_WINDOW);
} catch (Exception e) {
}
String cpuStat2 = linuxUtils.readSystemStat();
String pidStat2 = linuxUtils.readProcessStat(pid);
float cpu = linuxUtils
.getSystemCpuUsage(cpuStat1, cpuStat2);
if (cpu >= 0.0f) {
_printLine(mOutput, "total", Float.toString(cpu));
}
String[] toks = cpuStat1.split(" ");
long cpu1 = linuxUtils.getSystemUptime(toks);
toks = cpuStat2.split(" ");
long cpu2 = linuxUtils.getSystemUptime(toks);
cpu = linuxUtils.getProcessCpuUsage(pidStat1, pidStat2,
cpu2 - cpu1);
if (cpu >= 0.0f) {
_printLine(mOutput, "" + pid, Float.toString(cpu));
}
try {
synchronized (this) {
wait(CPU_REFRESH_RATE);
}
} catch (InterruptedException e) {
e.printStackTrace();
return;
}
}
Log.i("THREAD CPU", "Finishing");
}
});
return CpuUtil.monitorCpu;
}
/** Stop CPU monitoring */
public static void stopCpuMonitoring() {
if (mHandlerThread != null) {
monitorCpu = false;
mHandlerThread.quit();
mHandlerThread = null;
}
}
/** Dispose of the object and release the resources allocated for it */
public void dispose() {
monitorCpu = false;
if (mOutput != null) {
OutputStream os = mOutput.getOutputStream();
if (os != null) {
Streams.close(os);
mOutput.setOutputStream(null);
}
mOutput = null;
}
}
private static void _printLine(TestReport output, String process, String cpu) {
output.stampln(process + ";" + cpu);
}
}
