Consequences of changing USERPostMessageLimit

winapi

One of our legacy applications relies heavily on PostThreadMessage() for inter-thread communication, so we increased USERPostMessageLimit in the registry (way) beyond the normal 10.000.

However, documentation on MSDN states that "This limit should be sufficiently large. If your application exceeds the limit, it should be redesigned to avoid consuming so many system resources." [1]

Can anyone enlighten me as to how exactly consuming too many system resources manifests itself? What exactly are system resources? Can I somehow monitor an application's usage of system resources? Any information would be very helpful in deciding whether it is worth the time and effort to redesign this application.

Best Solution

The resources it is refering to are those used by the threads for receiving/handling the messages. You can monitor the thread pool size & other resources using the Taskmanager (look at View->Select Columns). It it may help you identify the specific resource if the consumer is resource locked, look for a resource count that tops out even while your threads are increasing.

However; if you need to increase USERPostMessageLimit then message producer is simply overloading the message consumer; by increasing this limit you are compounding your problem not fixing it. Reducing USERPostMessageLimit back to the default, and if your message producer cannot post the message try sleeping before retrying, allowing the consuming thread to clear some messages.

Related Solutions

C# – Changing master volume level

Okay, here goes:

const int MAXPNAMELEN            = 32;
const int MIXER_SHORT_NAME_CHARS = 16;
const int MIXER_LONG_NAME_CHARS  = 64;

[Flags] enum MIXERLINE_LINEF : uint{
    ACTIVE       = 0x00000001,
    DISCONNECTED = 0x00008000,
    SOURCE       = 0x80000000
}
[Flags] enum MIXER           : uint{
    GETLINEINFOF_DESTINATION     = 0x00000000,
    GETLINEINFOF_SOURCE          = 0x00000001,
    GETLINEINFOF_LINEID          = 0x00000002,
    GETLINEINFOF_COMPONENTTYPE   = 0x00000003,
    GETLINEINFOF_TARGETTYPE      = 0x00000004,
    GETLINEINFOF_QUERYMASK       = 0x0000000F,

    GETLINECONTROLSF_ALL         = 0x00000000,
    GETLINECONTROLSF_ONEBYID     = 0x00000001,
    GETLINECONTROLSF_ONEBYTYPE   = 0x00000002,
    GETLINECONTROLSF_QUERYMASK   = 0x0000000F,

    GETCONTROLDETAILSF_VALUE     = 0x00000000,
    GETCONTROLDETAILSF_LISTTEXT  = 0x00000001,
    GETCONTROLDETAILSF_QUERYMASK = 0x0000000F,

    OBJECTF_MIXER                = 0x00000000,
    OBJECTF_WAVEOUT              = 0x10000000,
    OBJECTF_WAVEIN               = 0x20000000,
    OBJECTF_MIDIOUT              = 0x30000000,
    OBJECTF_MIDIIN               = 0x40000000,
    OBJECTF_AUX                  = 0x50000000,
    OBJECTF_HANDLE               = 0x80000000,
    OBJECTF_HMIXER               = OBJECTF_HANDLE | OBJECTF_MIXER,
    OBJECTF_HWAVEOUT             = OBJECTF_HANDLE | OBJECTF_WAVEOUT,
    OBJECTF_HWAVEIN              = OBJECTF_HANDLE | OBJECTF_WAVEIN,
    OBJECTF_HMIDIOUT             = OBJECTF_HANDLE | OBJECTF_MIDIOUT,
    OBJECTF_HMIDIIN              = OBJECTF_HANDLE | OBJECTF_MIDIIN
}
[Flags] enum MIXERCONTROL_CT : uint{
    CLASS_MASK        = 0xF0000000,
    CLASS_CUSTOM      = 0x00000000,
    CLASS_METER       = 0x10000000,
    CLASS_SWITCH      = 0x20000000,
    CLASS_NUMBER      = 0x30000000,
    CLASS_SLIDER      = 0x40000000,
    CLASS_FADER       = 0x50000000,
    CLASS_TIME        = 0x60000000,
    CLASS_LIST        = 0x70000000,

    SUBCLASS_MASK     = 0x0F000000,

    SC_SWITCH_BOOLEAN = 0x00000000,
    SC_SWITCH_BUTTON  = 0x01000000,

    SC_METER_POLLED   = 0x00000000,

    SC_TIME_MICROSECS = 0x00000000,
    SC_TIME_MILLISECS = 0x01000000,

    SC_LIST_SINGLE    = 0x00000000,
    SC_LIST_MULTIPLE  = 0x01000000,

    UNITS_MASK        = 0x00FF0000,
    UNITS_CUSTOM      = 0x00000000,
    UNITS_BOOLEAN     = 0x00010000,
    UNITS_SIGNED      = 0x00020000,
    UNITS_UNSIGNED    = 0x00030000,
    UNITS_DECIBELS    = 0x00040000, /* in 10ths */
    UNITS_PERCENT     = 0x00050000, /* in 10ths */
}
[Flags] enum MIXERCONTROL_CONTROLTYPE : uint{
    CUSTOM         = MIXERCONTROL_CT.CLASS_CUSTOM | MIXERCONTROL_CT.UNITS_CUSTOM,
    BOOLEANMETER   = MIXERCONTROL_CT.CLASS_METER | MIXERCONTROL_CT.SC_METER_POLLED | MIXERCONTROL_CT.UNITS_BOOLEAN,
    SIGNEDMETER    = MIXERCONTROL_CT.CLASS_METER | MIXERCONTROL_CT.SC_METER_POLLED | MIXERCONTROL_CT.UNITS_SIGNED,
    PEAKMETER      = SIGNEDMETER + 1,
    UNSIGNEDMETER  = MIXERCONTROL_CT.CLASS_METER | MIXERCONTROL_CT.SC_METER_POLLED | MIXERCONTROL_CT.UNITS_UNSIGNED,
    BOOLEAN        = MIXERCONTROL_CT.CLASS_SWITCH | MIXERCONTROL_CT.SC_SWITCH_BOOLEAN | MIXERCONTROL_CT.UNITS_BOOLEAN,
    ONOFF          = BOOLEAN + 1,
    MUTE           = BOOLEAN + 2,
    MONO           = BOOLEAN + 3,
    LOUDNESS       = BOOLEAN + 4,
    STEREOENH      = BOOLEAN + 5,
    BASS_BOOST     = BOOLEAN + 0x00002277,
    BUTTON         = MIXERCONTROL_CT.CLASS_SWITCH | MIXERCONTROL_CT.SC_SWITCH_BUTTON | MIXERCONTROL_CT.UNITS_BOOLEAN,
    DECIBELS       = MIXERCONTROL_CT.CLASS_NUMBER | MIXERCONTROL_CT.UNITS_DECIBELS,
    SIGNED         = MIXERCONTROL_CT.CLASS_NUMBER | MIXERCONTROL_CT.UNITS_SIGNED,
    UNSIGNED       = MIXERCONTROL_CT.CLASS_NUMBER | MIXERCONTROL_CT.UNITS_UNSIGNED,
    PERCENT        = MIXERCONTROL_CT.CLASS_NUMBER | MIXERCONTROL_CT.UNITS_PERCENT,
    SLIDER         = MIXERCONTROL_CT.CLASS_SLIDER | MIXERCONTROL_CT.UNITS_SIGNED,
    PAN            = SLIDER + 1,
    QSOUNDPAN      = SLIDER + 2,
    FADER          = MIXERCONTROL_CT.CLASS_FADER | MIXERCONTROL_CT.UNITS_UNSIGNED,
    VOLUME         = FADER + 1,
    BASS           = FADER + 2,
    TREBLE         = FADER + 3,
    EQUALIZER      = FADER + 4,
    SINGLESELECT   = MIXERCONTROL_CT.CLASS_LIST | MIXERCONTROL_CT.SC_LIST_SINGLE | MIXERCONTROL_CT.UNITS_BOOLEAN,
    MUX            = SINGLESELECT + 1,
    MULTIPLESELECT = MIXERCONTROL_CT.CLASS_LIST | MIXERCONTROL_CT.SC_LIST_MULTIPLE | MIXERCONTROL_CT.UNITS_BOOLEAN,
    MIXER          = MULTIPLESELECT + 1,
    MICROTIME      = MIXERCONTROL_CT.CLASS_TIME | MIXERCONTROL_CT.SC_TIME_MICROSECS | MIXERCONTROL_CT.UNITS_UNSIGNED,
    MILLITIME      = MIXERCONTROL_CT.CLASS_TIME | MIXERCONTROL_CT.SC_TIME_MILLISECS | MIXERCONTROL_CT.UNITS_UNSIGNED
}

[StructLayout(LayoutKind.Sequential, CharSet=CharSet.Auto)]
struct MIXERLINE{
    [StructLayout(LayoutKind.Sequential, CharSet=CharSet.Auto)]
    public struct TargetInfo{
        public uint   dwType;
        public uint   dwDeviceID;
        public ushort wMid;
        public ushort wPid;
        public uint   vDriverVersion;
        [MarshalAs(UnmanagedType.ByValTStr, SizeConst=MAXPNAMELEN)]
        public string szPname;
    }

    public uint            cbStruct;
    public uint            dwDestination;
    public uint            dwSource;
    public uint            dwLineID;
    public MIXERLINE_LINEF fdwLine;
    public uint            dwUser;
    public uint            dwComponentType;
    public uint            cChannels;
    public uint            cConnection;
    public uint            cControls;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst=MIXER_SHORT_NAME_CHARS)]
    public string          szShortName;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst=MIXER_LONG_NAME_CHARS)]
    public string          szName;
    public TargetInfo      Target;
}
[StructLayout(LayoutKind.Sequential, CharSet=CharSet.Auto)]
struct MIXERCONTROL{
    [StructLayout(LayoutKind.Explicit)]
    public struct BoundsInfo{
        [FieldOffset(0)]
        public int    lMinimum;
        [FieldOffset(4)]
        public int    lMaximum;
        [FieldOffset(0)]
        public uint   dwMinimum;
        [FieldOffset(4)]
        public uint   dwMaximum;
        [FieldOffset(8), MarshalAs(UnmanagedType.ByValArray, SizeConst=4)]
        public uint[] dwReserved;
    }
    [StructLayout(LayoutKind.Explicit)]
    public struct MetricsInfo{
        [FieldOffset(0)]
        public uint   cSteps;
        [FieldOffset(0)]
        public uint   cbCustomData;
        [FieldOffset(4), MarshalAs(UnmanagedType.ByValArray, SizeConst=5)]
        public uint[] dwReserved;
    }

    public uint                     cbStruct;
    public uint                     dwControlID;
    public MIXERCONTROL_CONTROLTYPE dwControlType;
    public uint                     fdwControl;
    public uint                     cMultipleItems;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst=MIXER_SHORT_NAME_CHARS)]
    public string                   szShortName;
    [MarshalAs(UnmanagedType.ByValTStr, SizeConst=MIXER_LONG_NAME_CHARS)]
    public string                   szName;
    public BoundsInfo               Bounds;
    public MetricsInfo              Metrics;
}
[StructLayout(LayoutKind.Explicit)]
struct MIXERLINECONTROLS{
    [FieldOffset(0)]
    public uint   cbStruct;
    [FieldOffset(4)]
    public uint   dwLineID;
    [FieldOffset(8)]
    public uint   dwControlID;
    [FieldOffset(8)] // not a typo!  overlaps previous field
    public uint   dwControlType;
    [FieldOffset(12)]
    public uint   cControls;
    [FieldOffset(16)]
    public uint   cbmxctrl;
    [FieldOffset(20)]
    public IntPtr pamxctrl;
}
[StructLayout(LayoutKind.Explicit)]
struct MIXERCONTROLDETAILS{
    [FieldOffset(0)]
    public uint   cbStruct;
    [FieldOffset(4)]
    public uint   dwControlID;
    [FieldOffset(8)]
    public uint   cChannels;
    [FieldOffset(12)]
    public IntPtr hwndOwner;
    [FieldOffset(12)] // not a typo!
    public uint   cMultipleItems;
    [FieldOffset(16)]
    public uint   cbDetails;
    [FieldOffset(20)]
    public IntPtr paDetails;
}
[StructLayout(LayoutKind.Sequential)]
struct VOLUME{
    public int left;
    public int right;
}
struct MixerInfo{
    public uint volumeCtl;
    public uint muteCtl;
    public int  minVolume;
    public int  maxVolume;
}

[DllImport("WinMM.dll", CharSet=CharSet.Auto)]
static extern uint mixerGetLineInfo      (IntPtr hmxobj, ref MIXERLINE pmxl, MIXER flags);

[DllImport("WinMM.dll", CharSet=CharSet.Auto)]
static extern uint mixerGetLineControls  (IntPtr hmxobj, ref MIXERLINECONTROLS pmxlc, MIXER flags);

[DllImport("WinMM.dll", CharSet=CharSet.Auto)]
static extern uint mixerGetControlDetails(IntPtr hmxobj, ref MIXERCONTROLDETAILS pmxcd, MIXER flags);

[DllImport("WinMM.dll", CharSet=CharSet.Auto)]
static extern uint mixerSetControlDetails(IntPtr hmxobj, ref MIXERCONTROLDETAILS pmxcd, MIXER flags);

static MixerInfo GetMixerControls(){
    MIXERLINE         mxl = new MIXERLINE();
    MIXERLINECONTROLS mlc = new MIXERLINECONTROLS();
    mxl.cbStruct = (uint)Marshal.SizeOf(typeof(MIXERLINE));
    mlc.cbStruct = (uint)Marshal.SizeOf(typeof(MIXERLINECONTROLS));

    mixerGetLineInfo(IntPtr.Zero, ref mxl, MIXER.OBJECTF_MIXER | MIXER.GETLINEINFOF_DESTINATION);

    mlc.dwLineID  = mxl.dwLineID;
    mlc.cControls = mxl.cControls;
    mlc.cbmxctrl  = (uint)Marshal.SizeOf(typeof(MIXERCONTROL));
    mlc.pamxctrl  = Marshal.AllocHGlobal((int)(mlc.cbmxctrl * mlc.cControls));

    mixerGetLineControls(IntPtr.Zero, ref mlc, MIXER.OBJECTF_MIXER | MIXER.GETLINECONTROLSF_ALL);

    MixerInfo rtn = new MixerInfo();

    for(int i = 0; i < mlc.cControls; i++){
        MIXERCONTROL mxc = (MIXERCONTROL)Marshal.PtrToStructure((IntPtr)((int)mlc.pamxctrl + (int)mlc.cbmxctrl * i), typeof(MIXERCONTROL));
        switch(mxc.dwControlType){
        case MIXERCONTROL_CONTROLTYPE.VOLUME:
            rtn.volumeCtl = mxc.dwControlID;
            rtn.minVolume = mxc.Bounds.lMinimum;
            rtn.maxVolume = mxc.Bounds.lMaximum;
            break;
        case MIXERCONTROL_CONTROLTYPE.MUTE:
            rtn.muteCtl = mxc.dwControlID;
            break;
        }
    }

    Marshal.FreeHGlobal(mlc.pamxctrl);

    return rtn;
}
static VOLUME GetVolume(MixerInfo mi){
    MIXERCONTROLDETAILS mcd = new MIXERCONTROLDETAILS();
    mcd.cbStruct       = (uint)Marshal.SizeOf(typeof(MIXERCONTROLDETAILS));
    mcd.dwControlID    = mi.volumeCtl;
    mcd.cMultipleItems = 0;
    mcd.cChannels      = 2;
    mcd.cbDetails      = (uint)Marshal.SizeOf(typeof(int));
    mcd.paDetails      = Marshal.AllocHGlobal((int)mcd.cbDetails);

    mixerGetControlDetails(IntPtr.Zero, ref mcd, MIXER.GETCONTROLDETAILSF_VALUE | MIXER.OBJECTF_MIXER);

    VOLUME rtn = (VOLUME)Marshal.PtrToStructure(mcd.paDetails, typeof(VOLUME));

    Marshal.FreeHGlobal(mcd.paDetails);

    return rtn;
}
static bool IsMuted(MixerInfo mi){
    MIXERCONTROLDETAILS mcd = new MIXERCONTROLDETAILS();
    mcd.cbStruct       = (uint)Marshal.SizeOf(typeof(MIXERCONTROLDETAILS));
    mcd.dwControlID    = mi.muteCtl;
    mcd.cMultipleItems = 0;
    mcd.cChannels      = 1;
    mcd.cbDetails      = 4;
    mcd.paDetails      = Marshal.AllocHGlobal((int)mcd.cbDetails);

    mixerGetControlDetails(IntPtr.Zero, ref mcd, MIXER.GETCONTROLDETAILSF_VALUE | MIXER.OBJECTF_MIXER);

    int rtn = Marshal.ReadInt32(mcd.paDetails);

    Marshal.FreeHGlobal(mcd.paDetails);

    return rtn != 0;
}
static void AdjustVolume(MixerInfo mi, int delta){
    VOLUME volume = GetVolume(mi);

    if(delta > 0){
        volume.left  = Math.Min(mi.maxVolume, volume.left  + delta);
        volume.right = Math.Min(mi.maxVolume, volume.right + delta);
    }else{
        volume.left  = Math.Max(mi.minVolume, volume.left  + delta);
        volume.right = Math.Max(mi.minVolume, volume.right + delta);
    }

    SetVolume(mi, volume);
}
static void SetVolume(MixerInfo mi, VOLUME volume){
    MIXERCONTROLDETAILS mcd = new MIXERCONTROLDETAILS();
    mcd.cbStruct       = (uint)Marshal.SizeOf(typeof(MIXERCONTROLDETAILS));
    mcd.dwControlID    = mi.volumeCtl;
    mcd.cMultipleItems = 0;
    mcd.cChannels      = 2;
    mcd.cbDetails      = (uint)Marshal.SizeOf(typeof(int));
    mcd.paDetails      = Marshal.AllocHGlobal((int)mcd.cbDetails);

    Marshal.StructureToPtr(volume, mcd.paDetails, false);

    mixerSetControlDetails(IntPtr.Zero, ref mcd, MIXER.GETCONTROLDETAILSF_VALUE | MIXER.OBJECTF_MIXER);

    Marshal.FreeHGlobal(mcd.paDetails);
}
static void SetMute(MixerInfo mi, bool mute){
    MIXERCONTROLDETAILS mcd = new MIXERCONTROLDETAILS();
    mcd.cbStruct       = (uint)Marshal.SizeOf(typeof(MIXERCONTROLDETAILS));
    mcd.dwControlID    = mi.muteCtl;
    mcd.cMultipleItems = 0;
    mcd.cChannels      = 1;
    mcd.cbDetails      = 4;
    mcd.paDetails      = Marshal.AllocHGlobal((int)mcd.cbDetails);

    Marshal.WriteInt32(mcd.paDetails, mute ? 1 : 0);

    mixerSetControlDetails(IntPtr.Zero, ref mcd, MIXER.GETCONTROLDETAILSF_VALUE | MIXER.OBJECTF_MIXER);

    Marshal.FreeHGlobal(mcd.paDetails);
}

This code is huge and ugly. It's a translation of some C++ code, and with having to define all the P/Invoke stuff, it's a lot more code. But I've tested it, and it works. To use it, you simply need something like:

MixerInfo mi = GetMixerControls();
AdjustVolume(mi, 100);    // add 100 to the current volume

MixerInfo mi = GetMixerControls();
AdjustVolume(mi, (mi.maxVolume - mi.minVolume) / 10);    // increase the volume by 10% of total range

MixerInfo mi = GetMixerControls();
SetVolume(mi, mi.maxVolume);    // let's get this party crunk'd!

MixerInfo mi = GetMixerControls();
SetMute(mi, true);    // shhhh!!!!!!

WARNING

Due to the use of fixed-sized ints and field offsets, this may fail fantastically on 64-bit Windows. I don't know, I haven't tested it and haven't paid enough attention to know if these field sizes expand to 64 bits. caveat codor

EDIT

For the sake of simplicity (relatively speaking), I've left out any error handling. You should really check the return codes of all the mixerXXX functions, but I'll leave that as an exercise for the reader (read as: I was too lazy to do this).

C++ – Changing window background colour

Use the SetClassLongPtr function with the GCLP_HBRBACKGROUND argument:

SetClassLongPtr(windowHandle, GCLP_HBRBACKGROUND, brushHandle);

http://msdn.microsoft.com/en-us/library/ms633589%28VS.85%29.aspx

Best Solution

Related Solutions

C# – Changing master volume level

C++ – Changing window background colour

Related Question