c# - What is the best way to wait to next line from a fast-growing file? -

i need read fast-growing test file, , process new lines asap. file can updated several time per millisecond.

1. if introduce sleep @ "problem" line of code (as below), works nicely introduce 1 millisecond delay.

2. if comment out "problem" line, no delay cpu usage gets toward 70%.

is there better way resolve this?

public void updatepricesfromsfile() {     using (txtfilereader = new streamreader(file.open(filename, filemode.open, fileaccess.read, fileshare.readwrite)))     {         txtfilereader.basestream.seek(0, seekorigin.end);         while (true)         {             while ((line = txtfilereader.readline()) == null)             {                 system.threading.thread.sleep(1); //problem             }             //process line         }     } } 

extending comment code sample :

public abstract class filewatcher {     // last known position of stream      int m_laststreamposition;      // flag check if file in read state     volatile bool m_isreading;      // info file     fileinfo m_fileinfo;     // file system watcher      filesystemwatcher m_watcher;      // standard ctor used watch specific file     public filewatcher(string filepath)     {         // create new instance of filesystem using path of file         m_fileinfo = new fileinfo(filepath);         // if ( !m_fileinfo.exists ) throw new invalidargumentexception("filepath");         // start watcher based on fileinfo         m_watcher = new filesystemwatcher(m_fileinfo.directoryname, m_fileinfo.extension);         m_watcher.enableraisingevents = true;         m_watcher.changed += whenfilechanged;          // reset stream position , read file initialy         m_laststreamposition = 0;         readfile();     }      // event fired when file changed     // !! note fire whenever create file in same     //    directory desired file , same extension     //    , change/modify file     void whenfilechanged(object source, filesystemeventargs e)     {         // based on note comment, check if that's our desired file         if ( e.fullpath != m_fileinfo.fullname ) return;          // refresh informations file         m_fileinfo.refresh();         // check if added file,         // in case removed (?) reset laststreamposition (?)         if ( m_fileinfo.length <= m_laststreamposition )             m_laststreamposition = 0;          // read file         readfile();     }      void readfile()     {         if ( m_isreading ) return;          m_isreading = true;          using ( streamreader reader = m_fileinfo.opentext() )         {             reader.basestream.position = m_laststreamposition;             string line = string.empty;             while ( ( line = reader.readline() ) != null )             {                 processline(line);             }             m_laststreamposition = reader.basestream.position;         }         m_isreading = false;     }      protected abstract void processline(string line); } 

sample usage :

public class mefilewatcher     : filewatcher {     public mefilewatcher(string filepath)         : base(filepath)     {     }      protected override void processline(string line)     {         console.writeline ("new line added -> {0}", line);     } }  mefilewatcher mefilewatcher = new mefilewatcher("d:\\testdata\\mefile.txt");