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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple style='word-wrap: break-word;-webkit-nbsp-mode: space;-webkit-line-break: after-white-space'><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Tony et al:<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>On the surface, it would seem this convoluted code is doing the following:<o:p></o:p></span></p><p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo2'><![if !supportLists]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><span style='mso-list:Ignore'>1.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Making rd.buff appear as an “ARRAY OF <b>Byte</b>”, vice an “ARRAY OF <b>CHAR</b>, so as to meet the requirements of the File.T.read interface.<o:p></o:p></span></p><p class=MsoListParagraph style='text-indent:-.25in;mso-list:l0 level1 lfo2'><![if !supportLists]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><span style='mso-list:Ignore'>2.<span style='font:7.0pt "Times New Roman"'> </span></span></span><![endif]><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Limiting the buffer to be the smaller of “BIG”, or the actual number of elements in rd.buff<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Now, re #2, the code in FileRd seems to allocate buffers in 4096-char arrays, and BIG is 16M, so I don’t quite see why the need to ensure the buffer is limited to no more than BIG, as it should never be more than 4096.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>All that aside, are you concerned that the GC could be relocating rd.buff after its address is obtained and fed to the File.T.read (rd.sourceH.read) procedure?<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>If indeed this movement can occur, this code definitely needs to change.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>How can we force the GC not to move rd.buff, or is there another “safe” way to make rd.buff appear as an “ARRAY OF Byte” to satisfy the File.T.read interface?<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Buffers are allocated in line #45 as a <u>traced</u> reference to an ARRAY OF CHAR via:<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'> rd.buff := NEW(CharBuffer, BufferSize);<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Yet, the ByteArrayPtr in FileRd.m3 (line 25) is an <u>untraced</u> reference (to an array of Byte).<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Should we be allocating buffers (rd.buff) as <u>untraced</u> refs instead, and then explicitly freeing? Or, is there a way to keep them as traced refs, but avoid collection/movement while being used in an unsafe manner?<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Finally, there are multiple statements in the FileRd.m3 module similar to line #83 that must be dealt with (e.g., 114, 119).<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Regards,<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Randy Coleburn<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal style='margin-left:.5in'><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Tony Hosking [mailto:hosking@cs.purdue.edu] <br><b>Sent:</b> Wednesday, March 16, 2011 8:14 PM<br><b>To:</b> Coleburn, Randy<br><b>Cc:</b> m3devel<br><b>Subject:</b> Re: [M3devel] thread test results on Win7 64-bit<o:p></o:p></span></p></div></div><p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p><p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:12.0pt;margin-left:.5in'>This is the offending line:<o:p></o:p></p><div><div><p class=MsoNormal style='margin-left:.5in'>On Mar 16, 2011, at 6:50 PM, Coleburn, Randy wrote:<o:p></o:p></p></div><p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:12.0pt;margin-left:.5in'><o:p> </o:p></p><div><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'>***</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><o:p></o:p></span></p></div><div><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'>*** runtime error:</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><o:p></o:p></span></p></div><div><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'>*** An array subscript was out of range.</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><o:p></o:p></span></p></div><div><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'>*** file "..\src\rw\FileRd.m3", line 83</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><o:p></o:p></span></p></div><div><p class=MsoNormal style='margin-left:.5in'><span style='font-size:10.0pt;font-family:"Courier New"'>***</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif"'><o:p></o:p></span></p></div></div><p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p><div><div><p class=MsoNormal style='margin-left:.5in'> n := rd.sourceH.read(<o:p></o:p></p></div><div><p class=MsoNormal style='margin-left:.5in'> SUBARRAY(LOOPHOLE(ADR(rd.buff[0]), ByteArrayPtr)^, 0,<o:p></o:p></p></div><div><p class=MsoNormal style='margin-left:.5in'> MIN (NUMBER(rd.buff^), BIG)), mayBlock := NOT dontBlock)<o:p></o:p></p></div></div><div><p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p></div><div><p class=MsoNormal style='margin-left:.5in'>I am very suspicious about this... anyone have any insights?<o:p></o:p></p></div><div><p class=MsoNormal style='margin-left:.5in'><o:p> </o:p></p></div></div></body></html>